Locklin on science

Bad models and the end of the world

Posted in econo-blasphemy, stats jackass of the month by Scott Locklin on March 23, 2014

I loathe journalism as a profession: a claque of careerist whores, half-educated back-slappers and propagandists for the oligarchical lizard people who are ruining civilization. I loathe “science journalism” particularly, as they’re generally talking about something I know about, and so their numerous impostures are more obvious.

Journalists: they're mostly like this

Journalists: they’re mostly like this

Today’s exhibit, the “NASA study predicting the end of Western Civilization.” The actual study can be found in PDF format here. If you read the “journalism” about this in the guardian, cnet, or wherever else, it’s all about our impending doom. Not only do scientists tell us we are doomed, fookin’ NASA scientists tell us we are doomed.

The authors of the study are not NASA scientists. The NASA subcontractor  associated with this paper would like you to know this; probably because NASA was annoyed their name was associated with this paper. The only contribution NASA made was in partially supporting an institution which partially supported one of the three authors for one semester. The author in question,  Safa Motesharrei is a grad student in “public policy” and “mathematics” at U Maryland. The other two authors are also not NASA scientists. One is allegedly a professor of … political science in Minnesota -and more recently some cranky looking outfit called “Institute of Global Environment and Society.” The other one is a professor of the U Maryland department of Oceanic and Atmospheric sciences. Unless you consider the partial ramen noodle stipend one grad student received for one semester to be “funding,” or you consider NASA’s subcontractor to be liars, NASA did not fund or endorse this study in any meaningful way. Journalism 101, failed before even getting to the content of the article.

The three authors of this study

The three authors of this study

For what it is worth, had I published anything my sophomore year of grad school instead of trying to build a crazy vacuum chamber and catch a venereal disease, I’d have had some words in my paper thanking NASA for their support as well. This is despite the fact that most of my money came from the NSF and the University I was attending. I wasn’t in any way a NASA scientist. My institution wasn’t NASA affiliated. But we did get a NASA grant that paid for at least a month’s salary for me over the course of a year. When you get those grants, you say “thank you.”

Nafeez Ahmed, the imbecile at the Guardian who broke the story, continues to insist that NASA funded this study, despite the fact that they didn’t. I guess when someone Discovers you are a shoddy journalist, the accepted thing to do these days is doltishly double down on your error. Ahmed, of course, works for some preposterous save-the-world outfit, which apparently means he can pretend he is a journalist and doesn’t have to tell the truth about anything.

Journalistic failure is to be expected these days, and NASA scientists say stupid things all the goddamned time. Still, reading the paper itself was informative. Had anybody bothered to do so, the story would have been murdered in infancy. It’s one of the godawful silliest things I have ever read.

There is a fairly standard model from ecology called the “predator prey” model. Predator/prey models were  mostly developed to model exactly what it sounds like: things like wolf and moose populations in a National Park. The model makes assumptions (that predators are always hungry,  the prey will never die of old age, and  there are no other predators or prey available, for just a few examples of the limitations of the model), but if you set these equations up right, and the parameters and conditions are non-degenerate, it can model reality reasonably well. It’s really no good for predicting things, but it’s OK for modeling things and understanding how nature works.  The equations look like this, where x(t) is the predator population, y(t) is the prey population and a is predator birth rate, b is the predator death rate, c is the prey’s birth rate, and k is the predation rate; all rates are constant.

\frac{dy}{dt} = ay(t)x(t) -bx(t)

\frac{dx}{dt} = cy(t) -kx(t)y(t)

The predator/prey model is elegant, concise, and in some limited circumstances, occasionally maps onto reality. It is, of course, a model; there is no real reason to model things using this set of differential equations, and a lot of reasons not to. But sometimes it is useful. Like most good models, it is simple and doesn’t have too many parameters. Everything can be measured, and interesting dynamics result; dynamics that we can observe in nature.

The authors of this doom-mongering paper  have  transformed that relatively simple set of equations; a set of equations which, mind you, produces some fairly complicated nonlinear dynamics, into this rather un-handy mess, known as HANDY (for “Human And Nature DYnamics”):

\frac{dx_c}{dt} = \beta_c x_c(t) - \alpha_c x_c(t)

\frac{dx_e}{dt} = \beta_e x_e(t) - \alpha_e x_e(t)

\frac{dy}{dt} = \gamma (\lambda -y(t)) y(t) - \delta x_c(t) y(t)

\frac{d \omega}{dt} = \delta y(t) x_c(t) - C_c(t) - C_e(t)

In this set of equations, x_c(t) is the productive peasant population, x_e(t) are the population of parasitic elites, y(t) is “natural resources” and w(t) is “wealth.” \lambda is a “saturation of regrowth of nature rate.” \gamma is an “exponential growth of nature rate.” \delta is a “depletion of nature” rate term. C_c(t), C_e(t) are wealth consumption rates.

to make it even more complex: \alpha_c(t), \alpha_e(t), C_c(t), C_e(t) are all functions of \omega(t), x_c(t), x_e(t)

C_c(t) = min(1,\frac{\omega(t)}{poor(t)}) s x_c(t)

C_e(t) = min(1,\frac{\omega(t)}{poor(t)}) \kappa x_e(t)

poor(t) = \rho x_c(t) + \kappa \rho x_e(t)

poor(t) is some threshhold wealth function, below which you starve, and allegedly \rho is supposed to be a minimum consumption per capita, but it really makes no sense based on the equations. s is some kind of subsistence level of wealth and \kappa is the multiple of subsistence that elites take.

Instead of contenting themselves with constant predation or death rates, this train-wreck insists on making them the following:

\alpha_c(t) = \alpha_m + max(0,1-\frac{C_c(t)}{s x_c(t)}) (\alpha_M - \alpha_m)

\alpha_e(t) = \alpha_m + max(0,1-\frac{C_e(t)}{s x_e(t)}) (\alpha_M - \alpha_m)

Where \alpha_m, \alpha_M are constants for a normal death rate and a death rate where you have a high death rate, where, and I quote the paper directly: “when the accumulated wealth has been used up and the population starves.”

It’s worth a look at what they’re implicitly modeling here by adding all this obfuscatory complexity. All of the following assumptions are made by this model. Very few of them are true in reality. Most of these assumptions are designed to get the answer they did.

  1. The natural resources of the earth is well modeled by the prey equation
  2. The natural resources of the earth regenerate themselves via a logistic function
  3. There are two classes of humans
  4. There is a thing called “wealth” that is consumed by the two classes of humans at different rates
  5. The elite class of humans preys on the peasants and produces nothing
  6. The peasant class is all equally productive
  7. Wealth comes from peasants exploiting nature
  8. Elites all have \kappa times a subsistence income, rather than a smooth distribution of incomes
  9. Peasants all have s , a subsistence income, rather than a smooth distribution of incomes
  10. An extra variable called “wealth” is needed to make sense of these dynamics, and this variable maps onto the thing known in common parlance as “wealth.”
  11. The wealth factor could sustain a human society for centuries after ecological collapse (page 18)
  12. Death rates increase as natural resources are consumed at a faster rate (everything about modern civilization indicates the exact opposite is true)
  13. The peasants get nothing from the elites except population control
  14. Technological change is irrelevant (yes, they argue this; page 7)
  15. This ridiculous spaghetti of differential equations actually models something corresponding to Human Civilization

There are more assumptions than this, but you get the idea: this model is ridiculous, over parameterized, and designed to get the answers that they did. If you assume parasitic non-productive elites, you get the situation where social stratification can help “cause” collapse. Of course, if you assume parasitic non-productive elites, you’re assuming all kinds of ideological nonsense that doesn’t map well onto reality.

If you assume natural resources also act like prey, you can get situations where the natural resources collapse, then the society collapses. This is no big surprise, and you don’t need these obfuscatory complications to say this: it’s in the predator-prey equations already. Why didn’t they just model humanity and nature as simple “predator/prey” above? I am guessing, because nobody would buy it if you say things that simply, and it wouldn’t be an original paper. It also doesn’t allow them to pontificate on egalitarian societies.

As for the additional “wealth” factor these clowns use to distinguish themselves from an earlier bad model; as far as I can tell, the only purpose served by this degree of freedom is making it easier to mine way more natural resources than we actually need to support a population (something that wouldn’t happen in a standard predator-prey model). It also doesn’t make any sense, modeled in this way, unless you believe grain silos contain centuries worth of corn, or that people can eat skyscrapers. That’s how their wealth equations work; they actually assume you can eat wealth.

sandwich-board-man-warns-us-of-impending-doom

Dr. Nafeez Ahmed: Guardian columnist who broke this story

I actually feel a bit sorry for these guys, even though they are unashamed quacks. They didn’t ask to become this famous. Somehow the zeitgeist and some imbecile activist newspaper reporter decided to make them famous as people who are really bad at modeling anything. God help these people if they attempt to model something real, like chemical reaction dynamics, or, say, the earth’s atmosphere.

Returning to the mendacious loon, Ahmed, who brought this paper to world fame and attention. He asserts that the paper actually compares historical civilizations using this model. It does nothing of the sort. The paper mentions historical civilizations, but they don’t even make legalistic arguments that, say, the ancient Egyptians, whose civilization lasted for thousands of years, somehow follow these equations.  All they say is, ancient cultures were cyclical; they rise and fall; something everyone has known from the time of Heraclitus. Cyclical behavior does not imply this complex pastiche of differential equations; there are cyclical behaviors in nature which can’t be modeled by any differential equations. Finally, Ahmed asserts that the model predicts things. It doesn’t; nor does it claim to. It claims to model things. Modeling things and predicting things are very different.

The model itself was bad enough. What the activist-reporter said about it is inexcusable. The fact that everyone credulously picked up on this nonsense without questioning how Nafeez Ahmed made his living is even worse. Science by activist press release. Yeah, thanks a lot, “science journalists.” Nobody even noticed the clown who broke this story is a goddamned 911 truther.

A more reliable narrator than the Ahmed bozo who broke this story

A more reliable narrator than the Ahmed bozo who broke this story

I find all this intensely sad. I’m sad for the boobs who wasted their lives cranking out a model this useless. I’m sad for our civilization that it is possible to make a living publishing rubbish, and that talented people can’t make a living doing interesting and correct research which will benefit humanity. I’m also sad that journalists aren’t fired over their credulity regarding this fraud. I’m sad that ideological hogwash is published in all the papers as some kind of scientific truth, while nobody notices simple things, like the fact that the world fisheries are presently undergoing collapse, or the fact that there are no more rhinos because Chinese people haven’t discovered viagra yet.

I’m also sad that people are so obsessed with the end of the world. Maybe some day we’ll experience some kind of ecological apocalypse, or the imbeciles in the White House will nuke the slightly less stupid cavemen in the Kremlin. Chances are pretty good though, that before these things happen, we will all be dead. Wiser men than me have pointed out that anxiety about the end of the world is a sort of transference for anxiety about their own impending demise. As Spengler put it, “perhaps it is not the end of the world, but just the end of you.”

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18 Responses

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  1. Brian said, on March 23, 2014 at 9:01 am

    Another good one Scott. Love the pic of the Asian guy with sunglasses. Ha!

  2. Eivind Berge said, on March 23, 2014 at 9:32 am

    I am sure this is a very bad paper and all these objections are valid. But it seems to me you failed to point out the biggest flaw in the study: The model only includes renewable resources. It says on page 28: “This version of HANDY so far contains only one region, and only renewable natural resources.” Well, if you only take renewable resources into account, then you don’t get an industrial civilization in the first place, because our civilization runs on fossil fuels. And fossil fuels are depleting, or most importantly they are quickly getting more expensive to extract. The cost of extraction in the oil industry is currently rising by about 11% per year and this also applies to other mining. If you model the diminishing returns on resource extraction, then I think it easily becomes clear that we are headed for collapse. And forget the socialist nonsense as a solution, because there is no solution to the real peak oil crisis we are facing. Nothing can replace liquid fuels at the scale and cost and in the time frame needed. Technology is also powerless if we don’t have a good energy source to work with, and so far it looks like nothing can come close to oil. The energy return on energy invested (EROEI) from all renewable sources are too low to sustain an industrial civilization. I agree it’s unwise to focus too much on impending doom, but that doesn’t mean it’s not happening, and quite possibly in our lifetime.

    • Scott Locklin said, on March 23, 2014 at 7:23 pm

      I did mention that natural resources renew rates were modeled by a logistic function, but I didn’t actually use the phrase “renewable resources.”
      I don’t worry about peak oil, as I am aware of the existence of natural gas, coal and nukes. Life will suck more with an economy based on these things, but then, life already sucks more than it did when the population was only 3B people. I worry more about real problems, like the fact that only 1/10 of the population of the planet believes in conserving the fisheries.

      • Eivind Berge said, on March 25, 2014 at 8:30 am

        I hope you are right. No doubt we could theoretically have an economy based on coal, gas and nukes, but the peak oilers claim our economy is incapable of making the transition to a less useful energy source than oil without collapsing. Are you familiar with the work of Gail Tverberg and David Korowicz? For example, take a look at this paper by Korowicz:

        http://www.feasta.org/wp-content/uploads/2012/06/Trade-Off1.pdf

        Is this a bad model too? Is he wrong about how all the complexity and interdependencies make our civilization so fragile that we can only grow or die, and peak oil is sure to cause collapse? Here is also a good interview with him:

        http://www.resilience.org/stories/2014-03-19/how-to-be-trapped-an-interview-with-david-korowicz

        And how about Gail Tverberg:

        http://ourfiniteworld.com/

        Is she wrong when she claims that lack of investment capital will bring the whole system down? Do we not really rely on the ability to keep borrowing money in order to extract resources, which requires economic growth? It is a fact that oil companies have already started to cut back on exploration and sell off assets (a very recent development in the last few months) because the oil price is too low to finance new projects. It is hard to see how we could afford even more expensive substitutions and developments when the market will soon be unable to bear the cost of even drilling for oil. Any alternative technology will also require more energy and more oil, rather than less, at least during a transition.

        These peak oil writers believe the diminishing returns associated with peak oil will shortly cause a cascading collapse of the economy, followed by forced localization. And because we are totally dependent on the entire industrial system to extract resources and have anything more than stone-age technology, we will collapse back to the stone age in short order. And of course billions will die because there is no way to grow enough food like that. Only manual agriculture and wood for energy would be available. It would be nice if these doomers are wrong, but so far I have found so no flaw in their arguments. It would be helpful if you could explain exactly why they are wrong, because they don’t rely on so obviously bad models.

        • Kevin McGivern said, on March 25, 2014 at 7:18 pm

          If anyone is arrogant enough to model “civilization” in the way described, you might think they would at least match that level of confident ambition with some effort to model “human ingenuity” and ” potentially available energy” which in any macro model would seem to need to be measured as limitless. These may be useful pedagogic exercises (though I wonder) but such models are not “the world” and confusing the two seems not to bother you, you seem so determined to believe in such ill- founded prognostications

          • Eivind Berge said, on March 25, 2014 at 8:48 pm

            Human ingenuity can never beat the second law of thermodynamics, which is what we are up against here. We can be perfectly certain that civilization cannot subsist on an energy return on investment of less than 1:1, and in practice we will run into serious trouble long before that. Despite all our ingenuity, the energy return on investment of our major energy sources is steadily declining, as this article demonstrates:

            http://dx.doi.org/10.1016/j.enpol.2013.05.049

            The only hope is coal, which has an ambiguous trend in the US (but not in China). By switching to surface mining, it is possible to mine coal more efficiently. But the overall outlook is extremely bleak, and it is pretty clear that industrial civilization is winding down unless something unforeseen completely changes the energy paradigm. I just hope the descent will happen slowly so we don’t have to experience total collapse or even worse, survive into a future without modern amenities.

            • Kevin McGivern said, on March 25, 2014 at 11:51 pm

              There is so much of your Malthusian pessimism I could take issue with but lets assume these wholly inappropriate models are appropriate for the sake of argument. They hold only- in your own phrase “unless something unforeseen completely changes the energy paradigm” . And yet that, major technological responses to current problems, and not “extinction” are the very facts of history. The paradigm does indeed keep changing, notwithstanding your (or my) personal inability to see through the current problem. These types of models don’t even begin to “fit the data” on the scale they purport to address !

        • Scott Locklin said, on March 25, 2014 at 10:44 pm

          I’m not reading some 80 page people without a paycheck being involved. I think there are problems with contagion, and I would be happy to see the world go back to a multipolar system where it is difficult for capital to move around.

          The peak oil johnnies are right: unless Gold’s hypothesis is correct, eventually there will be no more oil. However, the doom fantasists are just wanking and fantasizing about a world they feel they’d like better. James Howard Kunstler for example: great writer, but a laugh riot as a futurist. He’s hoping obnoxious suburbs will go away with “peak oil.” Not as long as there’s coal and uranium to burn. The marginal costs of transportation are actually very small. When you look at a place like Ukraine where the people are really poor and gasoline costs are very high: it’s kind of a joke imagining people will somehow give up cars because gas costs too much.

  3. Kevin McGivern said, on March 23, 2014 at 5:21 pm

    Well yes. But if I were as clever as you Scott Locklin, I’d be taking on bigger and more important questions- this is just shooting fish in a barrel! The bigger issue is how to sensibly allocate economic resources to research in “public” higher education institutions. Journalism etc is not the issue here. I’m sure you know the bigger issue well and how thorny it is. But we lack intelligent analysis and elucidation of the issues even in the world of the scientific and economically literate.

    • Scott Locklin said, on March 23, 2014 at 7:42 pm

      In principle there are bureaucrats in charge of the NSF, NASA and DOE who are supposed to do this. I’m sure they’re physiologically capable of making such choices, but it has been a while since any bureaucrat has willingly cut their budget just because there is a lot of bullshit in it. So, it ain’t happening until the money flow is reduced, and their incentives are radically adjusted.
      Journalists certainly feed into this, as if you ever suggested cutting the budget that actually did fund this silly exercise, they would portray you as some kind of caveman who wants to destroy knowledge.

      There’s certainly something deeply wrong with the engineering and scientific community at present. There are more scientists and engineers alive now than ever in human history, but if you take away improvements in chip lithography, not much has happened since 1970 or so.

      My big old guess on the subject is that the training for engineering and science isn’t as difficult as it should be, and the number of people capable of doing the work is much smaller than the number of people presently claiming to do the work.

  4. Did Nasa fund ‘civilisation collapse’ study, or not? – News, Views and Reviews: Sid Harth said, on March 24, 2014 at 12:58 am

    […] http://scottlocklin.wordpress.com/2014/03/23/bad-models-and-the-end-of-you/ […]

  5. rene said, on March 25, 2014 at 1:05 am

    I have met Eugenia Kalnay before and she has done/(been associated with) good research that is essentially finding better ways to make short to mid-term weather forecasts with computers. Lately she has decided that she needs to do research on overpopulation, resource shortage catastrophe, and public policy. Her models rely on assumptions that were popular in academia in the late sixties and early seventies but are no longer taken seriously. She calls this “studying the human aspect of ecology and climatology” which is economics that ignores all the research economists have done. When I read this news report, I first thought immediately back to introductory calculus with predator/prey models because it split humans in to elites and commoners(predator/prey), and how you can easily create fudge factors that guarantee a desired outcome. I wanted to read the paper to confirm what I thought but could not find it. I agree that science journalists are worthless purveyors of quote-mined, anti-rigorous, partisan drivel and I think that all three of these authors should ashamed of being so sloppy. At least I expect more of a scientist than this. The authors whose degrees are in public policy are probably so solipsistic they are incapable of recognizing their own mathematical shortcomings. But Dr. K, from what I recall, is fairly intelligent. I suppose I can not speak with authority about her work because we are in different fields but I considered her political research to be tragic. I see no problem with more people being involved in science and engineering. I do see a problem with the virus that is the media conspiring to decide what is scientific and what isn’t and hardly a word from scientists who fear bad press.

    • Toddy Cat said, on March 25, 2014 at 7:32 pm

      A good example of the fact that expertise in one field is not necessarily transferable to another. It’s remarkable how few scientists recognize this.

    • Scott Locklin said, on March 25, 2014 at 10:48 pm

      Like I said, I don’t attribute any malice to anybody but the guy who broke this story. There are lots of people who say stupid things in the scientific community. I think it’s a shame so many are given to this kind of stuff. Someone besides me should be holding their feet to the fire for saying dumb things. We used to have journal editors for this.

  6. Carl said, on March 27, 2014 at 12:58 pm

    Hi. Long time listener, first time caller.

    As you say, “Modeling things and predicting things are very different.” Perhaps you could grace us young’uns, those aspiring to be non-jackasses, with a “Modeling vs. Predicting 101″ post? That strikes me as something that deserves to be revisited from time to time in an “Elementary Mathematics From An Advanced Standpoint” kind of way. I’d be willing to bet you’d have something interesting to say.

    • Scott Locklin said, on March 27, 2014 at 8:13 pm

      Well, in my world, it is kind of a tautology. Though thinking about it, the overloading of the word “model” makes my statement annoyingly vague and confusing.
      Basically, “modeling” like the one above can be used to examine the types of things which could happen in a dynamical system. Prediction, you’re trying to tell what will happen, which is a different goal. Of course, you’ll use some kind of model for prediction, but you’re often better off using a statistical or probabilistic model than the one you use to model the dynamics.

  7. […] econometrics (in econometrics you often force the structure of the results by model selection, see “Bad models and the end of the world” for some enjoyable vitriol on abuses of the […]


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