MCID: Minimal Climatically Important Difference

Guest Essay by Kip Hansen

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Warning: This essay is about a recently emerging concept being applied in medical research. In the course of the essay, it will become clear how this concept might cross over to the field of climatology. Those readers only interested in climate issues or the Climate Wars should move on to the next offering here at WUWT – this essay is not for you.

There is a new concept slowly emerging in the field of clinical medical research. It is called Minimal Clinically Important Difference.

Here’s the definition:

“When assessing the clinical utility of therapies intended to improve subjective outcomes, the amount of improvement that is important to patients must be determined. The smallest benefit of value to patients is called the minimal clinically important difference (MCID). The MCID is a patient-centered concept, capturing both the magnitude of the improvement and also the value patients place on the change. Using patient-centered MCIDs is important for studies involving patient-reported outcomes, for which the clinical importance of a given change may not be obvious to clinicians selecting treatments. The MCID defines the smallest amount an outcome must change to be meaningful to patients.” — Minimal Clinically Important Difference — Defining What Really Matters to Patients by Anna E. McGlothlin, PhD and Roger J. Lewis, MD, PhD

This concept can also be applied to outcomes are not patient-reported but which are simply measured numerically – such as blood pressure, body temperature, blood cholesterol levels and body weight or BMI.

Note: The first literature instance easily accessible is Measurement of health status: Ascertaining the minimal clinically important difference by Jaeschke, Singer and Guyatt (1989) doi:10.1016/0197-2456(89)90005-6 — after the turn of the century one finds more and more frequent references to his concept.

Let’s look at some examples:

Body Temperature:

We take our “temperature” to determine if we are ill or not. When we were children, our parents may have used an oral thermometer to determine whether we were too ill to attend school – if we had a fever, we stayed home – if not, off to school. It is generally accepted that normal body temperature ranges between 36.1°C (97°F) to 37.2°C (99.7°F) – alternately: the typical oral (under the tongue) measurement is slightly cooler, at 36.8° ± 0.4 °C (97.5°F to 99.5°F), with normal generally considered to be 98.6°F (and so marked on your mother’s glass oral thermometer). Well, we see right away that the term normal body temperature is not quite agreed upon. Nonetheless, there are things about body temperature that are clinically well understood: oral or core body temperatures above 100.4°F or so (for persons teenaged or older) is considered a fever and an indication of something wrong – such as an infection — high-grade fevers range from about 103°F-104°F — dangerous temperatures are high-grade fevers that range from over 104 F to 107 F or higher. Fevers are not only indicators of health problems but they can be dangerous in and of themselves. Temperatures below 95°F are considered dangerously low, verging on life threatening as core body temperature continues to fall lower.

Example: Let’s say we were researchers and wanted to test a fever-reducing drug. Various treatments that are supposed to affect body temperature, to treat fevers, would be judged by their action of changing the body temperatures of the patients in a clinical study – measured by thermometer. [Aspirin, for instance, is considered a fever-reducing drug and is often prescribed for just that purpose — it is one of many non-steroidal anti-inflammatory drugs.]

This concept of Minimal Clinically Important Difference calls for the researchers to determine in advance what numerical amount of change will represent the Minimal Clinically Important Difference – the numerical amount that must be surpassed for the results to actually mean that patients’ health has been improved in a way that is important to them – to the patients, to the patients’ health, not just to the doctors, not just numerical/statistical way.

In our body temperature example, it is apparent that lowering a raging fever of 105°F by 0.5°F to 104.5°F (but no lower) – even though it is a 7% decrease in the above-normal anomaly temperature – may not pass the Minimal Clinically Important Difference test – 104.5°F is still a raging fever and the patient may not be clinically better off. If the treatment does not bring it down by what was pre-determined to be the MCID (in this case, the MCID might be to reduce the fever to a certain level) then the treatment is less than successful or the effect of the treatment is not significant. It does not matter that the result – lowered average temperatures of patients in the study by 0.5°F – was found to be statistically significant if the result itself does not meet the pre-determined, and correctly identified, MCID.

Likewise, one could look at various treatments that lower a study cohort’s average of some metric – like blood pressure. This is often an approach used by epidemiologists looking at large health databases.

High Blood Pressure:

Note: Blood Pressure numbers represent another science war – though a quieter one. For many years, doctors considered 120/80 to be ideal and anything under 140 to be OK but now the threshold for hypertension has been dropped first from 160/100 to 140/90 and now, with prehypertension defined as 120/80 to 139/89, to where maximums of normal have been set at 120/80 – what used to be ideal is now the maximum acceptable before treatment is recommended. In the UK, however, blood pressures are usually categorized as: low (90/60 or lower), normal (between 90/60 and 139/80), and high (140/90 or higher). A recent study says doctors have been over-treating high blood pressure in seniors and that seniors should not be treated until their BP exceeds 150. And on it goes, with advocacy groups (and drug companies) pushing for the setting of official limits low and evidence-based-medicine doctors pushing back.

Example: Doctors wish to test a new blood-pressure-reducing drug. The doctors carrying out the study will be testing the drug on men with High Blood Pressure (US standard) >140/>90. Before anything else, they should define the MCID for blood pressure for this cohort – I don’t know what it would be, but they would have to set it before the study is carried out.

Let’s just guess that the average systolic blood pressure (the higher number) for the cohort is 150. In a cohort of 1000 men receiving treatment for high blood pressure (HBP) the study finds average reduction in systolic pressure to be 5 mm Hg, lowering the average to 145. Is this a MCID?

Well, I don’t know – the study’s authors would determine this by comparing their result with their pre-determined MCID. (In my opinion, 5 mm Hg with HBPs of 150 or so would not bring any one patient relief from the symptoms of HBP nor improve their health in any important way.) However, the result may have been found statistically significant with a very small P-value – it may just not be clinically important.

[ An aside: There is one more thing about many of today’s medical studies that is amusing – there might have been some effort in the above hypothetical blood pressure study to say that while that 5 mm Hg might not be much for individual patients it would be significant in public health setting (and I know this sounds crazy – but this really is claimed quite often in epidemiological studies) because 5 mm HG times 1,000,000 people is a huge reduction in public blood pressure! Epidemiological madness. ]

We have established that the Minimal Clinically Important Difference must be determined before the study is carried out, as part of the study’s planning and design. This is logical as the researchers must know in a general way what measurement tools to use – glass-and-alcohol oral thermometers or high accuracy digital thermometers, for instance. Or whether blood pressures should be determined my nurse-operated sphygmometers or mechanical digital equipment. What measurement scales to use: tenths of a degree C or thousandths of a degree C. How many subjects they must have to determine results to that accuracy or scale. There is no need for high accuracy thermometers if the MCID is “reduces body temperatures to within 1°F of 98.6°F”. No need for high-tech/high-accuracy blood pressure measurement tools if the MCID is “reduction of systolic blood pressure by 20 or more mm Hg.” Researchers comparing actual results with a pre-determined MCID will then know if their results will mean anything important for patients – to know if they really have a meaningful, clinically important, result.

So why is this concept being presented here at WUWT?

· First, because a pre-determined MCID is a very interesting addition to the scientific method in general. Requiring researchers to define what magnitude or type of result is clinically important (or in other fields: physically important, culturally important, militarily important, environmentally important, etc.) [Note that MCID may not apply in basic research in which one is simply trying to find out what there is to find out.]

· MCIDs become part of the study’s findings — just like methods and study design – and thus can be peer-reviewed. They can be taken into consideration when colleagues review (critique or praise) the resultant paper.

· MCIDs make it much more difficult to inflate the value of a research finding by disguising its insignificance. MCIDs can greatly reduce the bloat of “nothing-found” research papers being published – and the endless follow-on studies to those “nothing-found” studies.

Once you get the concept, you’ll be able to spot studies that should have been held to a MCID standard – that might better have been returned to the authors by peer-reviewers with a note: “What was the MCID for this study? Do you think that your result passed your MCID test?”

What does this have to do with climate science? Could or should such a concept be applied to climate science studies? If so, which ones and under what circumstances?

I will give just one example, and then we can all discuss this in the Comments.

Take a quick re-look (or first look) at my recent essay “Baked Alaska?…”. This essay includes some results that might have benefitted from the MCID approach. The basic hypothesis presented about the climate in Alaska is represented by Mike MacCracken’s, chief scientist for the Climate Institute, statement along the lines of ”how long-term trends will play out in Alaska” which are claimed to have been dangerously warming.

This one image gives us all the data in one go (enough for purposes of this discussion):

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Box (a), labelled 1920-2012, shows a long-term warming trends in 12 of 13 climate regions of Alaska, with the state-as-a-whole warming 0.9°C over the 92 year period. Box (d), labelled 1981-2012, however shows the entire state warming trend of only 0.1°C over the latest 31 years. The North Slope (at the top of the state) has a warming trend of 1.9°C over the same 31-year period. The climate region that includes Fairbanks, Alaska is shown with a 31-year cooling trend of -0.1°C.

Do you see where this leads? What is the Minimal Climatically Important Difference that we should be looking for in this data? Does Fairbanks’ -0.1°C 31-year trend meet a logical and scientifically supportable MCID for average temperature? Does the North Slope’s +1.9°C? Does it make sense to look at MCIDs for statewide annual temperature averages? Can a MCID even be set for annual average temperature alone?

Are there such things as Minimal Climatically Important Differences in climatology? Well, for Fairbanks, Alaska we find that despite 31 years of cooling trend their “# of frost free days” has increased by 50% since the 1920s (see the link Page 29). Now that’s a climatically important difference! The “fact” that the temperature has been trending down for a period long enough to be called climate disguises the climatically important difference of a significantly longer growing season – extremely important to this agricultural area – “one of Alaska’s premier agricultural regions and produces one third of Alaska’s agricultural products.”

Maybe climate science is spinning its wheels and wasting its time looking at all the wrong metrics….metrics for which one cannot define a logically and scientifically valid Minimal Climatically Important Difference. Instead, producing what Dick Feyman would have called “cargo cult science” – science aimed at supporting or proving one’s pet hypothesis instead of trying one’s darnedest to disprove it; spinning the narrative and the data to make one’s desired result look more probable, to make one’s itty-bitty “leans-my-way” result look strikingly significant.

Of a few things I am certain – one of them is that a difference in a couple of hundredths (“hottest year on record”) or tenths of a degree Centigrade of annual difference in the derived “apples-and-oranges” metric we know as “Annual Global Mean Temperature Anomaly Over Land & Sea” does not, and probably cannot, pass any possible scientifically valid Minimal Climatically Important Difference test.

 

In the same way, I would argue that nearly every political-boundary-based climate data set does not present any information that could lead to a valid Minimal Climatically Important Difference, based on the concept that political boundaries almost always comprise more than one climatic region (as in our Alaska example – for which 13 are proposed).

It does not help water-starved farmers in the Midwest to know that the farmers in the Central Hudson Valley of New York have adequate rain for their crops, thus keeping the CONUS Average Precipitation at an anomaly of zero against the 30-year average. Nor does it benefit the victims of Mississippi River flooding to know that their sorrow is not caused by climate change but rather just by a perfectly-historically-normal warm and rapid snow melt season hundreds of miles away. It is unlikely that small changes in annual average temperatures, measured and reported in single-digit tenths of a degree, are Minimal Climatically Important Differences but the differences within the same data set that reflect annual minimum temperatures, measured and reported in tens of degrees, might make the difference between wide-spread insect infestation with its resultant damage and freedom from serious insect damage – certainly a Minimal Climatically Important Difference. In this last case, the MCID might be whether or not it has remained continuously below -20°F for seven or more days.

I’ll start the comments off with this question: In all the issues that are considered here at WUWT – in all the numerical and statistical presentations of findings here, on other climate science sites and in the climate science journals-of-record – what type of results might inform science better if the concept of Minimal Climatically Important Difference was used in study design and results evaluation?

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Macro or Micro? While this photo looks like it could be some crystalline growth on a flat surface, looking a little chaotic with its resemblance to the Mandelbrot Set, it is actually: “Macro: Cumulus clouds over the South Pacific Ocean (Image created by Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC, additional image processing by Stephen Young.)”

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Author’s Reply Policy: My father was a doctor, an M.D., a pediatrician – I am not. The medical examples are written from a general public perspective. If there are medical errors – please inform, but do not blame. I use them only to make a point about MCID.

I am not particularly interested in climate science or the Climate Wars – my focus is more on science methodology, scientific ethics and science journalism, its use and misuse. This essay is about the concept of pre-determined MCIDs and their importance as an additional research method or tool – bridging the concept from its current use in clinical medicine to other fields – in this case, climate science. I’d like to hear your views.

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117 thoughts on “MCID: Minimal Climatically Important Difference

  1. Certainly something more rigorous than the ad hoc fitting of data to conclusions would be worthwhile. Worthwhile effort pointing to other science disciplines that are attempting to do so. Thanks,

  2. Germany regards hypotension as being a disease that needs treating.
    The overall average temperature variation, as claimed by the IPCC etc, is not really a useful measure to anybody outside of politics.
    If it’s a touch warmer at night, this will be beneficial, thus a max/min recording should be used.
    However, it’s never been about the science, only about the politics.

  3. I am reminded most strongly of Hippocrates’ oath:

      First, do no harm.

    NO climatologist nor politician citing c-limo-astrologists preaching their CAGW religion – and the “sacrifices” and “social cost of carbon” implicit within the c-limo-astrologists’ CAGW religion – can show that they are contributing to anything other than the deliberate death of millions, and the continued long-term harm to billions as they seek to artificially raise the cost of energy and restrict energy supplies to the world.

  4. Agreed “Maybe climate science is spinning its wheels and wasting its time looking at all the wrong metrics….metrics for which one cannot define a logically and scientifically valid Minimal Climatically Important Difference. Instead, producing what Dick Feyman would have called “cargo cult science” – science aimed at supporting or proving one’s pet hypothesis instead of trying one’s darnedest to disprove it; spinning the narrative and the data to make one’s desired result look more probable, to make one’s itty-bitty “leans-my-way” result look strikingly significant.”
    Despite the fact that critical analyses aimed at trying to disprove a hypothesis is the very foundation of the scientific process and scientific progress, there is an all out effort led by Trenberth, Mann, et al to smear anyone who does just that, labeling them as a “denier”. Their political efforts defile science.

  5. There is a similar concept in radiation protection called “Below Regulatory Concern”. As stated by Mr. Gallon above, any particular value is not about science, but politics. The BRC concept that some very, very small increment of radiation or radioactivity above natural background might not be of concern seems to be heretical.

  6. “Well, for Fairbanks, Alaska we find that despite 31 years of cooling trend their “# of frost free days” has increased by 50% since the 1920s (see the link Page 29). Now that’s a climatically important difference! “
    Climate science is an earth science. It studies a physical system. Climatically important differences are those that affect the physics. You are wanting to evaluate in terms of how it affects people. Now that is very imoortant, but is not the science. Climatically, the number of frost-free days on Baffin Island might be as important as in Fairbanks. And indeed, one day it might be an issue, if people try to grow things there. But that is not an issue for atmospheric science.
    Of course, the interest in climate science is how climate will affect people. But the science will be impaired if every sub-part is subject to a MCID test. As would medical science.

    • Reply to Nick Stokes ==> Quite right. Not every study could or should be subject to an MCID approach.
      However, if one is doing a study about climate for Fairbanks North Star Borough (county) then reporting to them that their county has been cooled 0.1°C over the last 31-years might not meet a Minimal Climatically Important Difference test….but reporting to them the fact of a 150% of frost free days is huge.
      What they used to call “pure science” was about just getting some hopefully-correct result — even if it were totally useless, it could still be important.
      To inform policy — less-than-MCID data is just more noise. I’m sure the County Board of Supervisors doesn’t want useless, insignificant numbers. They want data that makes a difference for them and their constituents.
      I can’t see how it would impair Climate Science, where applicable, to set MCIDs in advance for almost anything, if it were possible.
      We have all seen over the last week how silly it is to tout 0.02°C annual differences as significant or meaningful. If they had set some level of difference as MCID, they would have said, it appears that 2014 may be (38% chance) the hottest year on record by 0.02°C — but such a small difference is not a climatically important difference and is well within the margins of error of competing years.

      • “If they had set some level of difference as MCID”
        Well, a change of 0.1 or 0.2 °C isn’t MCID either, but would be >95% certain. In fact, as sometimes observed here, most of the short term changes are not MCID in the sense of directly affecting people. But they are worth studying – people like to know in advance, not after they have been affected.

      • Reply to Nick Stokes ==> Yes, exactly. 95% certain means something, it just doesn’t mean that the result is important. Remember, it is the authors of the study, in the design stage, that set the MCID based on their understanding and expertise. Other scientists then get to evaluate, review, and critique the MCID as well as the result when the study is published.
        Again, MCID might not be suitable for some types of studies.

    • But the MCID concept is important for policy. And you may have noticed, Nick, that climate science and policy are intertwined.

      • Nick etal I can see where MCID might restrict science. It is, or may be important to the folks. Why then do the modellers/politicians keep harping about 2C as if it is of any real significance? The only place I can see 2C being important is if it is the difference between freezing and not freezing. How can the difference in global temp between 14C and 16C be of any real significance?

    • “Nick Stokes January 22, 2015 at 3:45 pm
      “Well, for Fairbanks, Alaska we find that despite 31 years of cooling trend their “# of frost free days” has increased by 50% since the 1920s…”

      NB: The above quote is not Nick’s, only highlighted by Nick for additional discussion.
      From an ugly internment doing different jobs in a “Budget and Financial Analysis” department for a large organization including running the nut house…
      There are a many ways to cause me to grind my teeth during a presentation. Years of Budget work brings a very short temper when people misrepresent numbers even though I admit competency at doing the same thing; hey, my main job when employed is to always make my boss look good or better but I do draw the line at lies or illegalities.
      I despise pie-charts; pretty but basically useless and a big waste of ink.
      My suspicions grow whenever I see percentages without information.
      Agricultural Experiment Station Photograph Collection, Album 10.
      Page ten “Graph representing average number of frost-free days in Kodiak, Sitka, Matanuska, Fairbanks, and Rampart, 1921-1930, 10 year period.”
      Charts the average frost free days for Fairbanks Alaska.
      Period: 1921-1930
      Average “Frost free days” for Fairbanks, Alaska; 91.4 days.
      “Summary of Vegetable Variety Trials, Fairbanks, Alaska 1978-1985”, date of report 1989:
      “…Another important aspect of the climate is the amount of heat received during the growing season (approximately 90 frost–free days in Fairbanks)…” Remember this 1989.
      “Gardening in the Cabbage Patch in Fairbanks Alaska”, by Pat Babcock .

      “Reference: Interview with Carroll and Josie Phillips
      It is hard to believe we can grow apples in sub-arctic Fairbanks, Alaska.
      Carroll and Josie Phil lips, who operate a small nursery selling Siberian crabapples and pears, cotoneasters and honeysuckle, have an apple orchard! Carroll gave me a tour through his orchard the other day.
      He has been in Fairbanks for more than 40 years and knows a lot abo ut gardening both in the floor of the Tanana Valley and near the summit of the hill on which he lives off of Farmers Loop Road. He maintains you can get from 100 to 110 frost-free days when growing crops 600 to 900 feet above the Tanana Valley floor. The valley floor may have 90 frost-free days in comparison…”

      Our wonderful ever so trusted NCDC claims that Fairbanks, Alaska currently experiences 99 frost free days.
      Meanwhile the doofus, ( Mike MacCracken’s, chief scientist for the Climate Institute), Nick quoted, claims that Fairbanks has experienced a fifty percent increase in frost free days from the 1920s.
      Well, fifty percent of 91.4 is 45.7 which should combine into a rough total of 137 frost free days…
      I suspect that NCDC model output is the basis for MacCracken’s inflated extremely optimistic number. Fairbanks residents would be thrilled to get that long a growing season.
      NCDC’s inflated 99 frost free days, a 10% increase over the 1920s 91.4 frost free days, is likely a compilation of all temperature readings around Fairbanks. As the orchardist above noted, different altitudes around the city enjoy over a 10% increase over the valley floor. Cold sinks and collects in low spots.
      Fairbanks area weather stations illustrate the variety of locations the Fairbanks Station has enjoyed, finally ending up at the airport.
      I note that same station has what appears to be a step change up in temperature.
      Whenever someone, anyone claims wonderful percentages or waves pretty pictures, demand the background information and judge the results yourself.

      • Reply to ATheoK and Nick Stokes ==> Regarding Fairbanks Frost Free Days.
        First, the quote about Fairbanks Frost Free Days is from my original essay, in which I (Kip Hansen) state:

        “Well, for Fairbanks, Alaska we find that despite 31 years of cooling trend their “# of frost free days” has increased by 50% since the 1920s (see the link Page 29). Now that’s a climatically important difference!”

        The data for this quite is taken from “Climate of Alaska: Past, Present and Future”, a presentation by Dr. Uma S. Bhatt, Dept. of Atmospheric Sciences, University of Alaska Fairbanks, page 29, which presents this graph:

      • Well, I see entering an image didn’t work like it should, I’ll try again:
        As you can see, the data is credited to “G. Juday, UAF”, which is Dr. Glenn Juday, Professor of Forest Ecology, School of Natural Resources, UAF. He may be contacted there if there are questions about his data.
        The graph shows Fairbanks # of Frost Free Days increasing from approximately 80 at the left of the graph (early 1900s) to a guess-timate of average in the post 1990s of 120 — which is, more-or-less a 40 day increase, or 50% of ~80.
        The heading of “50% increase in growing season length” was apparently added by the maker of the slide.
        I used the data as an example only — not meant to be a statement of precise fact — of a Minimal Climatically Important Difference.
        I hope this helps to save ATheoKs teeth from being ground to stubs and absolves Nick Stokes from any blame for the statement.

      • Kip:
        A fifty percent increase in growing season (frost free) would be incredible anywhere.
        I understand you pulled the quote from elsewhere and I assigned the graph to a wrong person since the chart whose link you provided attributes ‘G. Juday UAF’ as the author.
        Leaving us with a quote, a silly chart (which doesn’t represent frost free days) and a stupendous claim.
        Frost free days are the average days between last frost and first frost over the previous ten years.
        Even with the cherry picked end period, they still didn’t reach fifty percent.
        I included several references above, two of them official;
        A presentation from University of Alaska archives.; given about 1935. 91.4 Frost free days.
        A statement from Alaska regarding testing the growth of different vegetables where they state the Frost free days for Fairbanks; Report was issued in 1989 and the Frost free days are set at 90 days..
        A recent quote from active orchardists in Fairbanks where they explain the differences in temperature depending on altitude. Frost free days, 90 days at the bottom of the valley and up to 110 higher in altitude.
        That entire presentation you provide the link to is a compilation of alarmist doom scenarios. Consider the changes in Arctic temperature; just what sensors provided those readings? Is this Paradise temperatures modeled and then smeared everywhere again?
        Finally, there is a statement that Alaska in in a cooling trend yet they claim an increase in growing season?
        Looking at the different trends for different temperature stations in Fairbanks, there is a clear trend (with step changes) for the Fairbanks station while the University station looks flat.
        I suspect the optimistic truth stretching ###### have been testing the little blue stained mushrooms.

      • Reply to ATheoK ==> Well, if it is that important to you, why don’t you contact Dr. Glenn Juday, Professor of Forest Ecology, School of Natural Resources, at University of Alaska, Fairbanks and see if you can sort out the data conflicts. I’m sure he’d respond to a pleasant inquiry. (As I have said, on onto another research project at the moment, but would be interested in the result.)
        It difference may be definitional …
        If you find out something interesting, post it here.
        – kh

  7. Great essay. Two analogies repurposed from medicine.
    1. First, do no harm. Which all CAGW prescriptions violate on both cost and reliability grounds. See Tol and Pielke Jr for many examples.
    2. Threshold effects. These have been established for medical stuff as diverse as radiation and (newly) BHP in plastic. Past interglacials (especially the last, the Eemian) mean they cannot be for the present. See my longish comments to yesterday’s Greenland melting model thread for examples and references. (I am presently too tired and tablet challenged to provide direct links for the lazy).

    • reply to Rud I ==> Thank you — and I agree about threshold levels and effects, which might well inform MCIDs.

    • Would these thresholds be applied globally or locally? (I’m thinking here about the sometimes ridiculous sounding warnings on some food ingredients or over-the-counter drugs where it states for some item: “Has been determined to be carcinogenic in the state of California.”)

      • A local difference would only apply if all californians were somehow genetically different from all other humans. You can take it from there. See essay California Dreaming for more of that states goofiness. Regards.

      • Reply to noaaprogrammer ==> The interesting thing is that MCIDs are set by the researchers doing the study, and set before the study begins, as part of the study design — so primarily, each study has a unique MCID.
        For certain types of studies, MCIDs might become standardized through repeated use and experience — for example in clinical studies of High Blood Pressure, researchers may, over time, settle into a generally agreed MCID for studies of treatments for High Blood Pressure.
        Climate studies are, in the present, all over the place — studies of temps vs. recruitment of rodent populations or polar bears, precipitation vs. soil moisture content vs. plant growth rates, hemispheric atmospheric phenomena vs. continental weather patterns, and on it goes. Many of these are “raw science” studies — “What is going on here?”. These types of studies probably would not have MCIDs but results might be evaluated in the conclusions or discussion sections of the resultant paper against a best guess posterior MCID — “Is this result likely to be climatically important? Important to the biosphere? Important to the human population? etc”.

      • Coming into this discussion late, but the idea is gaining traction in many medical studies by having the scientists define the MCID (among other things) prior to beginning the study and also guaranteeing to publish the results regardless of whether the critical values have been reached.
        This is to avoid to data dredging that has become the norm – ask enough questions and stratify your sample in enough ways and you will almost certainly find something “statistically significant” even though it is climatically/clinically/biologically meaningless.
        Climate studies should only be funded if the researchers state the methodology in advance – along with the MCID and they should also afree to report on the findings even if there is nothing significant. This is where clinical trials are moving in medicine (although it is still a fight).

  8. Applying an MCID concept to lowering are halting the rise in the globes average atmospheric anomily “fever” would be meaningless because no one knows what the optimum normal range should be. Also, the extremely expensive “clinical trial” of reducing anthropogenic emissions to reduce the so called fever will have considerable well established side effects.

  9. Until a “valid MCID” exists for CO2/GHGs and atmospheric/ocean warming feedback loops, absolutely everything else, sea levels, tropospheric/ocean/surface temperatures, ice cap extents, ad nauseum are nothing but sound & fury, signifying nothing.

  10. Great essay and great questions. The often posted global warming as seen on a mecury thermometer image speaks to this. The averaging and homogenizing of temperatures drowns and hides the essential questions being asked here. What folly that the MSN has missed asking these essential questions so many of us have been asking. Very instructive research analagy!

  11. Nothing new here but nice to present it.
    Scientists, particularly epidemiologists and modelers, will conduct “studies” on large number of individuals. Not only for pharmaceuticals but also for foods, coffee and red wine etc. Then they come up with some “statistically” significance differences. Such differences may be positive (red wine) or negative (coffee). Today in the newspaper it is pizza. Bad for you.
    This now get translated to red wine is significantly good for you and coffee is significantly bad for you.
    Notice, the word “statistically” is now removed, not only in the abstract of the “peer reviewed” article but also by the press. I call these “studies”, “surveys”. These “scientists” have no idea what is good or bad for you. They simply found a “statistically” significant change, positive or negative.
    The examples you gave, blood pressure, body temperature are perfectly good examples. The “scientists” never declare ahead of time what they will consider and important change (something you called a clinically significant change). They just go fishing with statistics.
    Now, take a look at the climate “scientists”. They do the very same thing. They do not declare ahead of time what they will consider “clinically” important for us. No. They just measure something and come up with a “statistically” significant change of something. This get translated to “significant” change and from there “important” change or even “catastrophic change”
    Here is how the USDA would look at it as a “clinicians” for climate change vs. food production and plant growth.
    Instead of looking at these “temperature anomalies” I would follow the USDA clinicians.
    The clinicians are the USDA climate zones or regions (obviously all available in most other countries as well).
    These clinicians have established not from “statistically significant” but from real data output what will grow in a region or zone. These “clinicians” will forget the “statistical significance” temperature anomalies for the USA for last year and tell you that the “averaging all the USA regions” yielding a “statistically significant increase” would be stupid. The northeast was extremely cold while the southwest was quite warm. Averaging this is stupid.
    But now, should they change the northeast regions. Absolutely not. Yes it was very cold, we all know this. Not enough to change what will grow and how much will grow and how we can adapt to it.
    It was so cold here in regions in the northeast that no local peaches were available. First time in 45 years. We adapted, plenty came from the southeast. Looks good for this year, much milder winter, no adaptation likely! Just back to having local peaches.
    So yes we have “clinically significant” results in medicine and weather. We need to listen to them instead of to the statisticians. Not that I am opposed to statistical analysis but we should know ahead of time what we think from booths on the ground what will be important.

  12. It looks like MCID just sets a limit for hypothesis testing, which isn’t a new concept. Most of the time it’s the 95% confidence limit. The important issue is what criteria make a valid measure. According to some statisticians, confidence is grossly overestimated in many cases, especially clinical studies. And people tend to mine their data to pass the test. Setting the MCID before the experiment is appropriate but not likely to be followed. Figure out how to strict enforce the protocol and you might have an improvement on current practice.

    • Reply to Gary ==> Good comment because many may have the same incorrect idea.
      Confidence Limit, Confidence Interval, Error Bars — all ideas about something quite different. These are statistical ideas and generally have to do with “the numeric range of the result that we believe the actual correct answer will be inside of 95% of the time.” Statistically significant results are often entirely clinically meaningless to patients in medicine studies despite being good solid results with tiny P-values.
      Nowhere near MCID, which calls for setting a minimum difference for results that will be important to the patient (in clinical medicine) or climatically important (climate science). You would not think that differences in daily average temperatures in your city would be important to you (or to the climate of your city) if they differed by a few degrees from one another — Tuesday average 72F Wednesday average 70F Thursday average 73…..this would be a perfectly normal late Spring here in Florida.
      However, in early Spring here in Florida, especially northern Florida, a drop in temperatures to below freezing on any night is a call to action for citrus growers. Tuesday low 36F, Wednesday low 34F, Thursday low WARNING expect 30F.. climatically important to the people here. If it did this repeatedly year after year — changing from a previous pattern of almost never below freezing — this would be an MCID for low temps in the Spring in northern Florida.

      • Exactly. Everything is local. Everything will be of importance to a particular group. In your case the citrus growers, in my case here the peach grower. Etc. Nothing new but important to note and present.

      • I’d have to do the data, but I’m not even sure that some of these variables are normally distributed. Usually one learns ahead of a study what sort of distribution you’re dealing with and that determines the appropriate statistical methods. I’ve seen very little reporting of that. As I said, I don’t know, but seems they all assume.

    • No Gary, your hypothesis is whether the MCID is reached and the stats should be applied to whether reaching it was statistically significant. otherwise, you are just talking about measurement accuracy.
      As an example, if you can only measure temp to 1 degree accuracy, you have to be over half a degree warmer to even measure this. You can make a number of measurements, but you will never be able to report that the temperature is 0.4 degrees warmer with any degree of confidence. But when you get a nice shiny new thermometer and can measure to 0.01 degrees, suddenly you are getting statistically significant results out the wazoo.
      If you define your hypothesis as whether the temperature has changed by half a degree, they you can say whether you results are a) measurable – depending on your system and b) statisticallt significant within whatever confidence limts you care to set. That is a proper hypothesis.

    • No, this idea is more useful. But it only relates to policy-making
      Regardless of whether GHGs control the climate, does this actually make a difference? Perhaps the cause a warming of 0.02°C per decade… would that matter?
      Decide in advance and then you can answer the question “So what should we do?”

  13. Kip,
    Thank you. Nice post. It’s a thought-provoking idea.
    I will not knock your idea simply because others will say it won’t work or won’t give it a chance to work because it becomes a threat to their entrenched thinking and belief system.
    There is so much wasted time, money and effort (intentionally, in many cases) arguing over how many hundreths of a degree can dance on the head of a pin — as if it matters to the planet.
    It DOES matter to those interests who desperately grasp at any straw to “prove” this or that part of their belief system.
    In the future, when science is full of people doing real science, and scientists don’t fear being wrong because it advances knowledge; and government’s interest is to better our cultural scientific skills and technology and not promote a falshood in the interest of power and control over their populace… then it would make sense, I think, to consider your Minimal Climatically Important Difference (MCID) so that we don’t end up chasing decimal points to nonsensical extents to prove a belief system, but instead develop true “trip wires” that might actually tell us something useful about our world.
    Do we need to shut down our power-generation systems because 2014 was 0.07 deg F “hotter” than ever?
    Should we instigate mass migrations to higher ground over a millimeter of sea level rise?
    What industry or jobs should be sacrified on the altar of a slightly less Arctic sea ice extent in some given year?
    It is all such a colossal waste. Time, money, effort and wasted “brain” power just to move a pawn on a chessboard that has no effect on the outcome of the game.
    Your idea, if implemented, could save us the money, the peer-reviewed pablum and the political speeches whereby the “leader of the free-world” calls over half his constituents “flat-earthers” as a means to embellish his ‘street cred’ with other like-minded, brain-dead, scientific zombies.
    I like your idea because instead of running in circles, we might actually be able to act like reasoned, intelligent, 21st-Century denizens of this planet.
    It would be so much more enlightened of us to deal with matters of consequence, rather than name-calling and chasing our tails and rolling out bread and circuses for the consumption of the blindly willing, the unknowing or the uncaring.
    Keep thinking!

    • and save us from uncountable (I’ve been trying) undergraduate and graduate degree programs that are figments of maximal money gathering scams which, thankfully, my children were never lured into.
      In human research, we have long had a sense of some outcome being biologically meaningful versus simply statistical – we could control many experiments so well that we knew there would be statistical significance, but so what. If done properly, even studies that did not produce statistical significance could in real peer review (not palsy) achieve recognition as showing something behaviorally important, interesting . . .and worth publishing. In my late dissertation, a lot of what wasn’t significant was real world important. At that time, writing one’s conclusions actually meant producing something meaningful and depended upon careful methods, calibrated instruments.
      This is a fundamental problem I have with this “research” in climastrology – seems they start with the results and finish right up with them too. That is carefully packaged for mass consumption, spun from any field anywhere into planetary peril. We have 3 or 4 of these presented to us daily (well not Bob or Willis), but you know which ones. They all begin to look the same to me.
      Thanks for a great post and really good idea. We can all take this away to those who struggle with alarmism and say “just ask so what”? and “who profits”?

  14. I’m not sure what a trend in the averages means anyway when there is such a large variation between regions. You can’t assume that any non-global changes at the stations give a nice symmetrical distribution around the 0.01-0.02°C per year rise common to all, and most people reading this will have little faith that its close enough to that after homogenization.
    I noticed that Australia’s women put on an average 4kg since the late 90s, or a bit over 2kg per decade. At that rate, most women will be 80kg+ in 100 years and there will be a dramatic increase in weight related deaths.
    I don’t know what the median was back then but the most recent study showed that there was a 4kg difference between the median and the mean until the 46-55 age group. Then the difference was only 2kg for higher age groups. A closer inspection showed the percentage of women that were 110+kg dropped by 50% going from 35-45 to 46-55. It looks like that its what it is to be morbidly obese is what is really rising. Apart from that group, nothing else seems to be changing.

  15. The absolute number one concern within the current study of climate science is whether or not increasing carbon dioxide in the atmosphere from burning of fossil fuels is causing harm by changing the climate in such a way that it causes harm to both animals and the top level animal, humans.
    My 5 years of study informs me that emissions of carbon dioxide is improving the world.
    My top concern is to present the best science possible, or the best knowledge we have about the world from a climate perspective. What this means is that I have to do an extraordinary quantity of study yet still on all aspects of climate science and spend extraordinary amounts of my time developing code for a system that will present the data to others. I am fortunate enough to have a wealthy benefactor that pays all my bills so that I can pursue this obsession I have for the next 5 to 10 years full time.
    More on topic, there are many climate indicators continuously changing throughout the world, from sea ice quantities, snow pack levels, rainfall etc., but temperature seems to be the number one metric for alarmism and in fact is the number one metric if carbon dioxide is the number one concern about global warming, making an assumption that carbon dioxide causes warming without the earth being able to respond with negative feedback.
    Fact of the matter is the best methodology to determine the average temperature of the earth just isn’t being done today. As a long time computer scientists that has also developed many other skills over the years and now has climate science as my number one pursuit for the foreseeable future (I even wake my self up from dreaming about arguing the facts with people), I intend to wrench climate science into our modern world with todays latest computing technologies now available to the ordinary person (well, the top 10% of the world anyway) as well as future technologies just around the corner.
    I would like to write more about what I am working on but I need to finish perhaps as long as 2 years of full time study. Let me finish by saying that it is the truth we at WUWT are pursuing and if we are correct, this truth will reveal itself, or win out in the end and new tools now under development will make this task easier.

    • Reply to garymount ==> Good luck with your ambitions. Hope to see some of your ideas presented here as Guest Essays. Info on submitting is here.

    • Me too and let me know if I can help.
      One of the troubles we face is a little outcomes based difference. We’d like to get back (or go forward) to decent science which is a process. Not what they want. They have already decided upon an outcome = CO2 is bad so quit the fossil fuels. Notice that only we talk about nuclear here.
      So they’ve selected the bad CO2 guy well – it is quantum mechanics to do some maths about radiative forcings to speak to some folks who fell asleep an hour ago. Mess that up with all carbon – disregard that were made of it and its plant food. it is just plain dirty and bad for you.
      Regularly we are presented with stories and, as Rud was exploring yesterday about Greenland, it is just a matter of how quickly we can drag them to their knees. I had hoped that the parade of failures would be compelling to others and that Earth is just peachy and taking care of her work, sustaining her plants and animals, burying way excess of C in bicarbonate, rolling heat out of the oceans . . . The dark side is strong.

    • Gary
      Congratulations on your obsession. I can’t think of a better topic for complete laser like focus. I hope you are including an intense interest in BEST since just a cursory analysis raised a lot of questions for me.
      There should be no shortage of fascinating subjects for you in the years ahead.

      • garymount
        All best wishes – you look like a well-experienced and well-skilled guy to do what you aim at.
        Please do not forget that the figures, the models, the hypotheses, must agree with real life – what’s outside the window, if you like.
        Do your numbers look reasonable?
        Ask yourself – and if wavering, ask on this site.
        There are many here with memories going back forty years – or more – in many continents, biomes, altitudes etc., and most, at least, will be willing & able to suggest if something ‘doesn’t look quite right’ – and often w h y it doesn’t.
        And remember – the oceans are jolly, jolly big . . . .
        Many thanks – and again, good luck!
        Auto

  16. The idea of a MCID is common sense. Reporting numbers without understanding their meaning or meaning-fullness is like playing checkers, interesting and fun but no value beyond that.
    In terms of Climate, I am not sure if a MCID is even possible. Even if we agreed the average temperature of 1850 to 1950 is our ideal state (like 98.6 for the body) and any deviation is a concern we still have no idea what amount of deviation is seriously problematic.
    We do know we do not want extremes like a new ice age. If temperatures once again started heading downwards, I imagine the climate gurus would have us producing more CO2 then ever before . In terms of heat, how much heat makes living impossible? The middle east is pretty hot and people have figured out a way to live there. It’s not the hot climate that is an issue for the people of the middle east, it is the constant war.
    I know the argument is that an increase in temperature creates more extreme weather, but scientifically this is unproven. There is not even enough evidence to warrant speculation. The speculation that happens regardless is hyperbole and rhetoric for political grandstanding; ie without scientific purpose.
    As is currently proven all over the globe, with our level of technology, expanding energy sources and good old ingenuity we are more than capable to adapt if not thrive in various weather climates.

    • Gets pretty chilly at night in winters in middle east. Need heat and bedding.
      I’d recommend (I know this is human centric) that looking at what environment most benefits life on this planet would provide good metrics if we could agree to them.

    • Reply to Alx ==> “In terms of Climate, I am not sure if a MCID is even possible.”
      Well, it would be difficult or impossible to set a logical and scientifically supportable MCID for “Annual Global Mean Temperature Anomaly Over Land & Sea” — other than a very high number — several degrees C, something out of bounds of historic (long long term) ranges.
      But “Global Climate” is itself a weird idea — what global climate? Thus Global Metrics are probably a fool’s errand — except for a few very specialized concerns.
      Climate, like sea level rise, is always local (though there are interconnections). So there are definitely MCID for studies about local climates — if Southern California shifted to the climate of NW California, that would certainly be Climatically Important. In the same area, if precipitation increases 50%, that’s certainly Minimally Climatically Important…..so there are areas of climate science that can have MCIDs set for studies done.

      • Kip- one obvious MCIP for the climate is “what is the maximal level of CO2 in the atmosphere that shows a measurable limit to increases in plant biomass(land+ocean)”. The Carboniferous period around 300 million years ago seems to show that higher CO2 greatly increases plant productivity. Obviously getting to a “sustainable” society with the current meager levels of plant grow is a hopeless dream.

    • We could set local MCIDs for local parameters. People know what they need.
      Not too wet here – will this change cause that to happen?
      Not too dry there…
      Maximum frequency of hurricanes in this place and minimum number of sunlight hours in that.
      Then it’s just a matter of negotiation between the Nations. Problem solved.

      • On this line of discussion, it is important “Too wet when?” “Too dry when?” “Just right when?” Timing is very important climatically — a sub-zero cold snap in January just means its a hard winter — but in April, it plays havoc with farmers and emerging plants.

      • This is what I would suggest in terms of policy relevant science. The researchers can do all of the basic research they like, but if you want to report on something policy relevant, you have to say what it is you are expecting to change and by how much. Temperature is not the issue from a global well-being point of view. You would have to pick something that matters (like growing degree days or earliest frost – to use the examples in the article), then define the MCID for that and test it – then your results will inform policy makers.
        If this was done for climate change, then the “catastrophic” element would be almost certainly removed and we would see it for what it is – something to be adapted to as human beings have done for millenia.

  17. MCID seems to me an extension of the older concept of effect size. Usually, effect size is expressed in standard errors and categorized as small, medium, and large. Required effect size is needed in power calculations for obtaining sample size with predetermined type I and II error rates.

    • Reply to Mindert Eiting ==> “MCID seems to me an extension of the older concept of effect size.”
      In clinical medicine, the distinction is what effect size is necessary to be clinically important to the patient.. We don’t care if the doctor thinks the result is impressive or really cool if it does not make a difference that is important to the patient and the patient’s health.
      How to apply this in climate science is one of the questions. Does Fairbanks really care if the 31-year average temperature has fallen 0.1°C? That, succinctly, is a “so what!”. Fairbanks having 50% more frost free days (a longer growing season by 50%) is very important to them.
      California getting 1 inch less rain, a small change in some places, is quite important to Californians.

      • Climate science needs to adopt the medical concept of “watchful waiting”. We may or may not have a real (actionable) problem. To adopt radical medical practices under these circumstances disobeys the concept of “first, do no harm”. The same principle applies to massive disruption of human society.

  18. Aren’t climate scientists doing something like MCID when they look at things like frequency of extreme temperatures, heat waves, droughts, floods, etc.? I would not say they do a very good job of it, but that seems to be the idea.
    One reason they do this is because seemingly insignificant average T changes can have large effects. For example, the 0.8 C temperature increase in Fairbanks causing a 50% increase in frost-free days.

    • Reply to Mike M ==> If you look at the “# of frost free days” graph (it is linked, you have to page down in the .pdf)) you’ll see that the increase is not just brought about the 0.8°C from 1900, but # of frost-free days continues to increase even through the latest 31-year cooling trend.
      I wouldn’t say the “extreme weather” thing is related to MCID. Certainly a doubling of the number of tornadoes in important though I don’t think they have a handle on how exactly climate relates/causes/prevents tornadoes.
      If a particular place had a change in some type of extreme event, like suddenly week long heat waves once a month, that might well be an MCID. But the fact that some place has “heat waves” which they have had before and will have again, is not necessarily a MCID…you see?

  19. Well the MCID is a practical means to quantify benefits while climate science is an attempt to quantify harm.
    But I get your point. That said, the mad mad world of climate science has already posted their version of MCID, hence the constant reference to “2 degrees above pre-industrial” as the “safe” limit for temperature increase. Problem being that the MCID as you have discussed it is arrived at be mitigating harm that is known from observation (a sustained fever of 107 will kill you) while the “safe” limit is simply quoted ad naseaum with no evidence, theoretical or otherwise, to back it up.
    So, while your point may have merit, it is predicated on the belief that the science being conducted is facilitated by the use of practical metrics that help quantify effects. The unfortunate truth is that climate science in general left any notion of practical metrics behind a long time ago for the simple reason that employing same would instantly expose the hypocrisy endemic to the field. Hence, we get papers quantifying organic carbon from melting glaciers in terms of fractions of a Mississippi River as one recent example. An honest metric would have exposed that in the context of the earth, the postulated results were a rounding error.
    There’s lots of other examples. My point being that for practical metrics to emerge in any given field of science, there has to be a goal that is served. Until the goal in climate science is to honestly evaluate effects instead of raising alarm, no practical metrics are likely to emerge.

    • Reply to davidmhoffer ==> That is insightful that the “2 degrees above pre-industrial” is a sort-of MCID — the limit that they feel will be importantly different.
      But you are right about the goal — ref: my comments about cargo cult science.

    • Agreed, davidmhoffer.
      Aside from the sheer lunacy of some of the works we see here, and the boundless faith to bind that with climate peril, most of the stuff we shoot down is based essentially in your “practical metrics “.

    • If you think we don’t know the “safe” limit of a sustained fever: “is quoted at naseaum with no evidence, theoretical or otherwise, to back it up”, then don’t show up at the emergency room with a fever of 102. Just stay home. We don’t need you at the emergency room telling us that you have no evidence that you are feeling terrible. Please stay home.

      • Reply to rd50 ==> I think your comment is a reply to davidmhoffer, who mixes the Climate Science 2°C above pre-industrial surface average with the human medical idea of a raging fever.
        I’m quite sure he means that the climate idea is unsupportable — not the medical idea.
        Personally, I wouldn’t go to the Emergency Room with a 102°F fever — I’d take 1 mg Aspirin and call myself back in the morning if I wasn’t feeling better.
        My wife and I recently returned from the northern Caribbean, where we did humanitarian work for many years, and there I would have immediately popped Cipro as well…and called my American doctor for a consult on symptoms.

      • Oops — I wouldn’t get much effect from 1 mg of Aspirin — I meant to type 1 gram (1000 mg) of Aspirin….

      • rd50
        I can’t tell if you misunderstood the reference, or if you are trying to make the case that, by way of analogy, a 2 degree increase in earth temperature is serious.

  20. I’d add, just because no one has brought it up so far:
    Climate Model outcomes are not data!
    Determine validity; demonstrate reproducability = essentials of the scientific method.
    If there is an Achilles heel, this is it. Outcomes have had no behavioral significance – minimal or otherwise – excepting public relations and political policy. Find some minimal acceptable level of model output.

    • just for this record, and I think it is a good record:
      The Computer Models can’t work – treating sets of chaotic systems with linear dynamics ain’t happening. There is simply nothing minimal about it.

      • Bubba,
        Agreed.
        There are many things that may, or do, affect the climate, including the local, regional and (if it is of value) global temperature [or Relative Humidity, or Insolation or Rainfall . . . .].
        This blog, WUWT, has a lengthy list I the sidebar.
        We are told that there are many things that have [or may have] caused the current plateau/pause in (if it is of value) the global temperature – over fifty of them I gather; maybe some ideas/hypotheses have value.
        Each, plainly, is believed by the watermelons, or some subset thereof, to be able to affect climate.
        And do we, the watermelons, or anyone else know which factors are important, which are marginal- ish, and which are utterly insignificant?
        No.
        So – “The science is settled” is plainly a political statement.
        Scientifically – it is a large steaming crock of what comes out of the south end of a north-bound bull, singularly lacking in constipation.
        “We need to tell you how to vote.
        “We need to direct you in how you travel to work/where you vacation/what foods you may eat.
        “We will prevent you from having children – or grand-children.
        “If necessary – and we will decide – we will eliminate you in your billions, so we may live in a ‘paradise’ with only a few hundred million/thousand people.
        “Now I’ve told you what’s coming – get the *%<ck off MY otherwise-perfect world."
        A bright outlook for humanity, with better plant-foods; or a horrid outlook?
        I know what I think. Have a great weekend, all
        Auto

  21. MCID in my view is a good idea. It will never happen. Too difficult to move the goalposts that way. They love their”science” built on shifting sands. Can’t even pin the clowns down on the difference between climate and weather. The crisis is always around the next corner, the language Orwellian. The only they succeeded in falsifying is their integrity.

    • Reply to logos_wrench ==> Ah, well, that is a different matter. The proponents of EBM (evidence-based medicine) have been hammering away for years and only slowly making inroads.
      The idea alone is interesting for those of us who read science studies, helping us to determine when we are seeing a study that would have benefited from the MCID approach. It changes one’s perspective just a little bit.

      • Understand EBM and inroads are slow, but perhaps insurance will be a force there.
        Problem is with the roots of science. We seem to be the last ones expecting that science can have the effect. Most can’t distinguish between legitimate efforts to do science and otherwise (to be fair) and I’ve been writing letters to local paper and they’ve actually been publishing them.
        Reactions to my letters are entirely about people’s beliefs and the science be damned. I learned the hard way a time ago that logic cannot combat feelings and beliefs. I continue to struggle with how perhaps common sense might help and it seems that this common sense might relate to a minimal real and perceived difference.
        Time for bed, but thanks for provoking thoughts.

    • The Senate said what we all know, that climate is changing and has always done so. Hence, climate change is not a hoax.
      The Senate made no determination regarding Catastrophic Anthropogenic Global Warming, CAGW or Climate Change run riot. This, we know, has all the earmarks of a hoax. I suppose that is about a chance of 1 in 10 billion that it is not a hoax.

  22. People may be all for carbon capture and storage, however they rarely have any idea how much reduction in temperature can be expected in 100 years if a billion dollars is spent on CCS. So if they were told the temperature would be 1/10,000 C lower in 100 years, would it be worthwhile?
    That assumes of course that you believe that an increase of 2 C would be catastrophic which I do not happen to believe.

  23. Not to worry about being off-topic in regard to climate studies. Let me thank you for the link to the AMA published study on treatment of hypertension. I have, for several months, been in the uncomfortable position of possibly declining to follow my doctors’ recommendation to continue using beta blockers and ace inhibitors to lower blood pressure from mid 130’s to “as low as we can get it.” (Currently 95-110) Problem is side effects, only there is nothing ‘side’ in the real world, only ‘effects.’ Dizziness, muscle aches, weakness, coughs–these effects are as real as the numbers on a blood pressure readout. It’s all about risk management, and a clinically minimal assessment should include all real risks.
    Just as poverty and misery are real effects of misguided climate policy.

    • Tell your doctors to drive their own BP down to 90/60 with a hot tub and, if necessary the same meds they think you need, stand up abruptly, then get back to you. Might enlighten them a bit about the need to provide adequate blood flow to the brain. (They might want to use a wrist type sphygmomanometer in the tub. They can calibrate it against a conventional forearm cuff in the office if they have, as they reasonably should, a few doubts about the wrist instrument). Other than that, do some research. You’ll probably find there are tens of thousands of papers on blood pressure and hypertension with remarkably little consensus.

    • Reply to Juan Slayton ==> You might print out the AMA study and send it to your doctor with a note. If you can’t spark a discussion with that, you might want to seek a second opinion.
      My [ non-doctor ] understanding is that BPs in the mid-130s need not be treated with drugs, especially if you are “older” like me.

  24. (In my opinion, 5 mm Hg with HBPs of 150 or so would not bring any one patient relief from the symptoms of HBP nor improve their health in any important way.)

    With the exception of an exceedingly rare but probably very serious condition called Malignant Hypertension, high blood pressure HAS no symptoms. It is correlated with a bunch of undesirable things, but for the most part causation is at best hazily defined. There may well be another, undiagnosed, condition that is causing the hypertension and treating the hypertension is may be, at best, cosmetic.
    That said, I agree that a 5mmHg reduction for any single patient is of dubious value. Hoiwever, there is a related argument that might have some merit which is that if a treatment demonstrates an average 5mmHg reduction and if treatment is actually required the drug may have more impressive affects for some individuals.

    • Reply to Don K ==> All valid medical points.
      The “the drug may have more impressive affects for some individuals” is perfectly true….this is where MCIDs are particularly useful…Does the treatment make an important difference for some individuals? Enough individuals to be still important in clinical practice?”
      A HBP drug that is found to be extremely successful with 20% of those treated might be a clinically important breakthrough.

  25. The concept can – should – also be applied to government policy.
    A number of years ago I complained about the Congestion Charge in London for example. The claim was that it would reduce commuting times by 10%. That sounds a lot until you think that commuting times are 40-60 minutes for most people. Thus I was being “saved”, at great expense and inconvenience, four minutes each morning.
    What exactly was I supposed to do with that four minutes?

    • Reply to Tim Hammond Jan 23 0243
      This is another example where a solution is sold on the basis of a statistic which has very little to do with the problem. Problem in the case of London was the inordinate number of cars entering Central London, which caused much of the traffic congestion (not all – some was caused by the buses, and possibly most by the interaction of buses and cars).
      Solution was to institute a boundary tax on entering Central London. I have checked the Wikipaedia article on the congestion charge, and find that there is no indication of any claim it would reduce commuting times by 10%. (There are mentions of improvements of from 30% in the early stages dropping to about 7% later). I suspect the claim was newspaper flummery, rather like the claim that the “Titanic” was unsinkable. What was intended was to improve the speed of buses and make their journey times more reliable (which it did), provide money for improvements to public transport (which it did and still does) and hopefully to reduce some of the pollutant gases from operation of motor vehicles – which it possibly does – there seems to be some disagreement.
      In general, it can be called a success in its original aims.
      If you did save four minutes travel time, you could always boil a couple of eggs and eat them on your way in, as long as the bus driver does not see you or the other passengers object. You thus improve your diet, to the benefit of your general health – the “Congestion Charge Is Good For You”

  26. Actually blood pressure could be a symptom of something else rather than its cause, as indeed is body temperature. We know for a fact that lowering an excessive body temperature or raising an abnormally low one is immediately beneficial to the patient, and therefore it is valid to address the sympton then go on to investigate the cause, although the body’s own mechanisms may well be able to do that inside the right temperature range. What is not so immediately obvious is that changing a high blood pressure conveys instant benefits (it may, but in the majority of cases it does not – this does not of course rule out long-term beneficial effects). Correction extreme blood pressure probably will stave off immediate effects, but the range of acceptable blood pressure readings (i.e. the numbers) is hugely greater than for body temperatures.
    If we now consider side effects, we enter a different realm. The side effects of the odd aspirin or paracetamol taken for a few days at most and at ‘on the packet’ doses are unlikely to lead to significant side effects, whereas long-term or huge dosages might. The treatments for high BP on the other hand, are ‘rest of your life’ treatments, and for these, side effects almost certainly will manifest themselves, possibly with a severity that is more inconvenient to the patient, and perhaps even life-threatening. For example, if the HBP medication increases cholesterol levels, and that requires a statin to treat – a statin that in fact affects the efficacy of the BP medication, but also leads to raised blood sugar levels and a diagnosis of type 2 diabetes, for which the treatment raises cholesterol levels and further affects blood pressure, then one enters a sort of medical equivalent of ‘whack-a-mole’.
    Moreover, we find that one or other of these medications might cause hives, increase of sensitivity to sunlight, muscle spasms and cramps of such severity that the patient is bedridden for months on end, blurred vision, mood swings, schizophrenia, suicidal thoughts, appearance of blotchy skin, growth of breasts and erectile dysfunction in men, loss of hair in women (and men, but many of them are baldies anyway), dizziness, joint pain, increased frequency of urination leading to severe loss of sleep – and one begins to wonder if the physician prescribing the drugs is not a greater hazard to the patient than the original symptom of HBP.
    In climate science, the application of the ‘cure’ has equivalent debilitating effects on our lifestyles and economies, for no observable effect on the climate, so it not only fails the minimal effect criterion, but also the ‘do no harm’ one.

    • Reply to Daft Lassie ==> Not so daft…your medical points are very good — and enter into the realm of MCIDs and MCIDs for side effects (negative MCIDs?).
      Juan Slayton, commenting above, can testify to the problems created by over-treating HBP.
      If you are a medical professional, perhaps you can advise him.

  27. This may be a version of the perennial idea that data analysis of outcomes should be done using a utility function. It’s been around a very long time, but never seems to be implemented to any degree. Presumably, people are wary of arguments over their chosen function (here MCID) in addition to all the other statistical problems?

    • Reply to basicstats ==> In clinical medicine studies the pre-determined MCIDs would be very pragmatic — does the patient feel better, is his condition markedly improved, both in the estimation of the patient’s doctors and the patient himself, does the patient think he is importantly improved?
      The MCID is unlikely to be a result of statistics, though it would certainly show in the statistical results. But just because there is a significant statistical result doesn’t mean there has been a Minimal Clinically Important Difference achieved.

  28. Climate Migration?
    What is the Minimal Climatically Important Difference in TEMPERATURE sufficient to cause climate migration?
    The alarmists claim: Climate-Induced Migration: A Looming Crisis

    Currently, it appears that the most widely accepted estimate of climate change-induced migration is 200 million–far more than the combined populations of France and Germany and almost two-thirds of the entire U.S. population. According to the Nansen Initiative, a program launched by the governments of Switzerland and Norway, natural disasters displaced an estimated 144 million people between 2008 and 2012.

    However, the FACTS, of people voting with their feet, show that:
    Census: Florida’s population overtakes New York’s

    Florida has passed New York in population to claim the rank of the USA’s No. 3 state, with almost 20 million residents, the Census Bureau reported Tuesday.
    California remains the most populous state, followed by Texas.
    Growing strongly again after the housing market’s collapse and the Great Recession, Florida added about 800 people a day in the past year — many of them New Yorkers, and many of whom, as former seasonal visitors, were affectionately called “snowbirds.” Earlier Census data showed that the Sunshine State is gaining about 25,000 more New Yorkers than it loses to New York each year.

    • Reply to CaligulaJones ==> Brignell’s Trojan Number is a spin technique to misrepresent the findings of a study.
      Had the author’s of the study being misrepresented in this way used a MCID approach, their results would have been already evaluated against a pre-set concept of what would be a clinically important finding — and the spin-meisters would not be able to get away with twisting the miniscule insignificant findings into something else.
      The MCID approach is very effective against these types of shenanigans.

      • Too true.
        Before the Amazing Randi walked back his true beliefs on climate change due to the typical anti-science backlash, he was one of my personal heroes (still is, but a bit…tarnished).
        He still created one of the better methods for dealing with folks with irrational beliefs: he lets THEM decide what the outcome is supposed to be, then creates the test they mutually agree upon.
        Of course, when they fail, the blame games gets into high gear. See: number of excuses for The Pause. What are we up to, 40?
        Sad that scientists are no more sophisticated than run-of-the-mill charlatans when it comes to making excuses.

  29. Coming into this discussion late, so my comments in reply to people’s posts are probably irrelevent now, but there are moves to have all clinical trials registered prior to commencement and to have their methodologies and end-points (whether using an MCID or not) listed in advance. This is being done specifically to prevent the kind of statistical shenanigins that has gone on for far too long. In addition, registered trials must have their results published somewhere – even if they are negative – to remove the publication bias that exists.
    This move is actually being supported by the pharmaceutical industry as they are actually the ones being fleeced by preliminary studies claiming positive effects that don’t hold up after they company has spent hundreds of millions on development. Throwing out useless treatments as early as possible is the biggest saving drug developers can make.
    [We’ll get into re-defining normal to “create” a a whole new class of people who nee treatment in another discussion. That is about increasing the use of a drug once it is known to have an effect.]

  30. Kip:
    Great thought provoking post. Might be a good idea, but I’ve already got my Doc ticked off at me.
    I was going for dendritic agate. Making my image identification only off a little, if we use a galactic system scale.

    • Reply to ATheoK ==> Dendritic agate would have been a good guess — I have seen polished slabs that look exactly like that – in fact, the local gem and rock club has their annual show in two weeks — which I will attend. Anyone near Cape Canaveral is welcome.

      • Kip, may you find the rocks you desire.
        I’m collect rocks too, well sort of. I’m not a labeler, but I love to go rock hunting and bring back piles. The best stuff gets a window display, the good stuff gets clear glasses, the humdrum get buckets and pails and what’s left goes in the garden and borders.
        I did come home with a granite slab from an old quarry. It was down a hill in the stream.
        Nothing like sending kids into the yard to search for crystals (Herkimer, Amelia county, Arkansas), fossils and stuff.
        I might’ve been a magpie, raven or a pack rat in a previous life… oooh, shiny, color…
        And yes, I’ve seen large thick slabs of polished dendritic agate that one can get lost in, like flying a small plane through Jupiter’s clouds.
        When I finished your essay and learned the image’s subject, I did go back and look again with a different viewpoint. Good stuff!

      • Reply to ATheoK ==> I once lived up above the Mohawk River in New York, and had Herkimer Diamonds in the creek behind our grist mill. My two oldest kids used to find them all the time.

  31. Using the medical analogy, Specialist prescribed new drug for my arthritis, it worked really well, my arthritis settled right down. I went to GP and asked about the intense headaches, he looked up new drug on MIMMS. Blood pressure was dangerously high. No problem he said we will control that with other drugs. i questioned his opinion, whoops, bad mistake and not done. Something told me I had a problem here, so I rang the drug manufacturing company and asked their opinion, and told them what my GP said, they wanted to know GP’s name and phone number, about an hour later, I got an abrupt phone call from GP, saying take no more of arthritis drug, and don’t take blood pressure tablets either. What can I say DUHHHHHH!!!!!!, and he has the university degree. Would have loved to have been a fly on that wall. I have found out that my instincts are better than all the training, and that I saved my own life in this instance. Yes we should listen to the Experts (drip’s under pressure), but we should also listen to those little voices in our own heads, that says something is wrong here.

    • Reply to lyn roberts ==> Glad you got it straightened out. I grew up n a home with a PDR (Physician’s Desk Reference ) on the living room table — I never take anything without fully reviewing the full data.
      The PDR saved me from the worst drugs of the 1960’s as well.

  32. EPILOGUE: Thanks for all of your input and conversation on the use of Minimal Clinically (or Climatically) Important Difference tests for various kinds of medical and climatic research studies.
    I’m off on another project now but if you wish to ask questions or comment on this topic, you can continue below or email me at my first name at the domain i4 decimal net.

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