Tag Archives: models in general

I mistrust models

This is not a new post, but I think it’s worth republishing some old ones given the serious proposals out there to radically alter our society and economy based on what models have predicted about our climate.

Here are three, the second with a few apocalyptic predictions from the past, the third about why the US was smart to withdraw from the Paris accord

I mistrust models.

I have no special mistrust of climate models, I mistrust all models of complex systems.  Here are six reasons why.

Reason #1:  My cousin runs an advisory service for institutional investors (hedge funds, retirement funds, stock market funds etc. etc.)  Here is the beginning of his latest post 16 June ’17

There were 3 great reads yesterday.

First was Neil Irwin’s article in the NY Times “Janet Yellen, the Fed and the Case of the Missing Inflation.”  He points out that Yellen is a labor market scholar who anticipated the sharp decline in the unemployment rate. However the models on which the Fed has relied anticipate higher levels of inflation. Yet every inflation measure that the Fed uses has fallen well short of the Fed’s 2% stability rate. If they continue raising short-term rates in the face of low inflation, then “real” rates could restrain future economic growth.

Second was Greg Ip’s article “Lousy Raise? It Might Not Get Better.” Greg makes the point that tight labor markets are a global phenomenon in many industrialized countries, yet wage inflation remains muted. Writes Greg “If a labor market this tight can’t generate better pay, quite possibly it never will in Germany & Japan.”

Third was an article by Glenn Hubbard (Dean of Columbia Business School & former chairman of the Council of Economic Advisors under George W. Bush). His Wall Street Journal op-ed was titled “How to Keep the Fed from Following its Models off a Cliff.”  Hubbard suggests that Fed officials should interact more with market participants and business people. And Fed governors should be selected because of their varied life experiences, and they should encourage a healthy skepticism of prevailing economic models.

Serious money was spent developing these models.  Do you think that climate is in some way simpler than the US economy, so that they are more likely to be accurate?  I do not.

Addendum 5 March 2019: In numbers just in today, US GDP grew by  3.1 percent between fourth quarter 2017 and fourth quarter 2018. The Federal Reserve’s December 2017 median projection of  growth for 2018 was 2.5%.  They were off by nearly 25%.  My wife’s college roommate is a very bright woman who worked for the Fed as a mathematical economist for years.  The problem is not her intelligence nor those of her colleagues, but the models they are using. 

Reason #2: Americans are getting fatter yet living longer, contradicting the model that being mildly overweight is bad for you.  It is far too long to go into so here’s the link — https://luysii.wordpress.com/2013/05/30/something-is-wrong-with-the-model-take-2/.

The first part is particularly fascinating, in that data showed that overweight (not obese) people tended to live longer.  The article describes how people who had spent their research careers telling the public that being overweight was bad, tried to discount the data. The best quote in the article is the following ““We’re scientists. We pay attention to data, we don’t try to un-explain them.”,

Reason #3: The economic predictions of the Congressional Budget Office on just about anything –inflation, gross national product, economic growth, the deficit — are consistently wrong — http://www.ncpa.org/sub/dpd/?Article_ID=21516.

Addendum 28 June “White house economists overestimated annual economic growth by about 80 percent on average for a six year stretch during Barack Obama’s presidency, according to Freedom Works economic consultant Stephen Moore.

Economists predicted growth between 3.2 to 4.6 percent for the years 2010 through 2015. Actual economic growth never hit above 2.6 percent.”

Reason #4:  Animal models of stroke:  There were at least 60, in which some therapy or other was of benefit.  None of them worked in people. It got so bad I stopped reading the literature about it.  We still have no useful treatment for garden variety strokes

Reason #5:  The Club of Rome,  — dire prediction based on a computer model which got a lot of play in the 70s.  For details see — https://luysii.wordpress.com/2017/06/01/a-bit-of-history/.  The post also has a lot about “The Population Bomb” and its failed predictions and also a review of a book about “The Bet” between Paul Ehrlich and Simon

Reason #6: Live by the model, die by the model. A fascinating book “Shattered” about the Hillary Clinton campaign, explains why the campaign did no polling in the final 3 weeks of the campaign. The man running the ‘data analytics’ (translation: model) Robby Mook, thought the analytics were better and more accurate (p. 367).

A bit of history

I’ve been reading Nature since I’ve been able to afford a subscription, e.g. since about 1972. To put their undoubted coming hysteria about Trump’s withdrawal from the Paris agreement into perspective, consider the fact that they bought the arguments of the Club of Rome, hook line and sinker. The Wikipedia article is quite sanitized, but here’s a direct quote from the jacket flap of the club’s book “The Limits to Growth” which came out in 1972.

“Will this be the world that your grandchildren with thank you for? A world where industrial production has sunk to zero. Where population has suffered a catastrophic decline. Where the air, sea and land are polluted beyond redemption. Where civilization is a distant memory. This is the world that the computer forecasts. What is even more alarming, the collapse will not come gradually, but with awsome suddenness, with no way of stopping it”

Well, it’s 45 years later and their grandchildren have seen no such thing. Nature’s online available archives go back to 1975, but I’ve been unable to find a link to one of their articles. If anyone out there has found one, post a comment.

When we were down in New Haven, I picked up a book by a Yale Prof, Paul Sabin called “The Bet” concerning the intellectual conflict between Paul Ehrlich — he of the population bomb and Julian Simon. Ehrlich said we’d run out of just about everything shortly (presumably because of too many people), so economist Simon bet him that we wouldn’t. The intellectual war began in earnest in the 80’s and dragged on for a decade or so.

I recommend the book. In it you will find John Holdren, Obama’s ‘science’ advisor, also a devout malthusian, although with a degree in physics.

Perhaps Nature has it right this time, and that the models of warming which failed to predict the climate stasis of 17 years duration (the term pause gives away the game implying that temperature will continue to increase) are a reliable guide to the future.

Even if Nature is right, the Paris Agreement was terrible, no verification, no penalties for missing targets etc. etc. A massive expansion of governmental control and clamps on economic expansion, for minimal benefit.

So relax. Protest if you wish, it’s a cheap display of virtue which costs you nothing, even though you’re quite willing to fight global warming down to the last coal miner.

A climate treaty based on a failed model, a victory for the political class

Scientific theories stand or fall based on the accuracy of their predictions. Exactly 100 years ago Einstein’s theory of  gravity was welcomed because it corrected an inacurate prediction of Newton’s theory.

It’s worth staying the course to follow what I’m about to describe. The orbits of all our planets are nearly circular — but not exactly so. A circle has a single center; an ellipse has two ‘centers’ (focal points). Planetary orbits have the sun at one focal point of the ellipse (this was known even before Newton). This means that every orbit has a point at which the planet is farthest from the sun (called the aphelion) and a point at which it is closest (the perihelion).

The perihelion doesn’t stay in the same place with each succesive orbit. Rather it moves — this is called the precession of the perihelion. Newton’s formulation of gravity predicted a certain rate at which the perihelion of the planet Mercury moved between sucessive planetary orbits — which was not corroborated by actual measurement.

Physicists a century ago were seriously exercised by this inaccuracy. So how large was it? Quite small. Recall that a circle contains 360 degrees. A degree is far too large for astronomical work. So each degree contains 60 minutes and each minute contains 60 seconds. So a second is 1/3600 of a degree. The discrepancy was a mere 43 seconds per CENTURY.

Contrast this with the inaccuracy of the models of global warming, NONE of which predicted the current stability of global atmospheric temperature as measured by satellite for the past 18+ years. It’s not that CO2 isn’t a greenhouse gas the accumulation of which (other things being equal) should reflect radiation back to earth and warm the planet. No one disputes that. It is the magnitude of the CO2 effect and the importance of other factors determining global temperature which is crucial. Clearly global temperature should have continued to rise in the past 19 years as CO2 rose. This is what the models on which the Paris agreement is predicated predicted But there has been  no rise.

It’s also fairly sleazy that all the ‘adjustments’ being made to temperatures as measured on the surface of the earth mostly adjust past temperatures downward to preserve the rise. Note that satellite temperatures are the most accurate we have and there is no way to adjust them. Unfortunately they just don’t go back that far.

It is far more accurate to say that global warming has stopped for the past 18+ years. Saying that it has paused implies that it will continue.  Some 50 post-hoc explanations of ‘the pause’ have been published.

Bottom line: the concern over global warming is based on models which have failed in their predictions of the present. There is little reason to regard them as more accurate for their predictions of the future.