Extreme Measures May Mislead
November 25, 2013 9:17 AM   Subscribe

How to think about "Science Studies Prove My Position", for politicians and all non-scientists. Any collation of measures (the effectiveness of a given school, say) will show variability owing to differences in innate ability (teacher competence), plus sampling (children might by chance be an atypical sample with complications), plus bias (the school might be in an area where people are unusually unhealthy), plus measurement error (outcomes might be measured in different ways for different schools). However, the resulting variation is typically interpreted only as differences in innate ability, ignoring the other sources. This becomes problematic with statements describing an extreme outcome ('the pass rate doubled') or comparing the magnitude of the extreme with the mean ('the pass rate in school x is three times the national average') or the range ('there is an x-fold difference between the highest- and lowest-performing schools'). League tables, in particular, are rarely reliable summaries of performance.
posted by Dashy (28 comments total) 16 users marked this as a favorite
 
Today's xkcd is relevant.
posted by Gelatin at 9:35 AM on November 25, 2013 [1 favorite]


These are all pretty good pieces of general statistical advice.

However, how many politicians actually want good scientific practice, even assuming they read this? The reason a lot of think tanks exists is exactly to produce just-so stories with scientific gloss that can be repeated context free in campaign speeches and news reports. Pretty much every part of that chain knows what they're doing, and don't give a shit about scientific validity and careful application of statistical analysis.
posted by codacorolla at 9:40 AM on November 25, 2013 [5 favorites]


Regression to the mean. It affects and infects so much erroneous inference. Variability is HARD.
posted by Mental Wimp at 9:45 AM on November 25, 2013


I think the key to helping people understand these concepts...politicians especially...is to not to make the explanations read like computer instructions. Do you think any politician is going to stick around long enough to try to understand "best-rate fallacies?" I'm not sure many of them even know what a "mean" is. Science is at a disadvantage because it is very rarely made digestable and as such is hard to learn passively. I feel like what we really need are folks who make an effort to explain difficult concepts in plain english who are more knowledgable than pop-science writers...
posted by jnnla at 9:45 AM on November 25, 2013 [1 favorite]


However, I must point out that the definition of a P-value given in the article is wrong:
Expressed as P, statistical significance is a measure of how likely a result is to occur by chance.
The P-value is the probability of observing an outcome at least as extreme as the one observed, assuming the null hypothesis is true, that is, the hypothesis one wants to reject or disprove. It is not the probability that the outcome occurred by chance. The difference may seem subtle, but it is very important in interpreting the results.
posted by Mental Wimp at 9:51 AM on November 25, 2013 [8 favorites]


Science is at a disadvantage because it is very rarely made digestable and as such is hard to learn passively. I feel like what we really need are folks who make an effort to explain difficult concepts in plain english who are more knowledgable than pop-science writers...

There's only so much you can do with explaining complicated topics to people who don't care and/or know about the subject.

Even a really good pop-sci writer mostly just gives you the impression that you understand something.
posted by empath at 9:51 AM on November 25, 2013 [2 favorites]


However, how many politicians actually want good scientific practice, even assuming they read this?

Enough that many policies are given trial runs with statistical measures. I think there's a planet money podcast that talks about this, but I could be mistaken. I'm pretty sure SuperCrunchers talked about it though.

However, I think it's naive to assume politicians don't understand science, logical reasoning or math. It's their electorate that doesn't understand these things, and their major donors that stand to profit so long as that remains the case.
posted by pwnguin at 9:52 AM on November 25, 2013 [1 favorite]


I can't put my finger on why, but something about the tone or writing style of that list turned it into blah blah Ginger when I read it, and I'm a stats type who is interested in policy.
posted by zippy at 9:56 AM on November 25, 2013 [2 favorites]


Randomization avoids bias. Experiments should, wherever possible, allocate individuals or groups to interventions randomly.

One way to randomize that's politically acceptable is to use a lottery for people who sign up for a program. Then all interested parties can be tracked to see if the program generates the actual benefits it is designed to yield.

The problem with this is that ideology drives too much of the political debate, and partisans are often afraid to test their favorite policy recommendations in a rigorous way.
posted by Mental Wimp at 9:56 AM on November 25, 2013


However, I think it's naive to assume politicians don't understand science, logical reasoning or math.

I think a great deal of them generally don't, even ones that are big supporters of scientific funding and NASA, etc. They often have an institutional trust in the scientific process, but that doesn't necessarily translate into an understanding of it.

It takes a lot of time to keep up with what's going on in science, and I can't believe that most representatives have the time to do it.
posted by empath at 9:59 AM on November 25, 2013


I work in social services and I really want a dress shirt embroidered with Goodhart's Law so that I can wear it to every meeting: "When a measure becomes a target, it ceases to be a good measure." There is so much hooing and hawing about the need for better evidence in my field, but we don't need better evidence in as much that we need better human beings. The second you incentivize something, you incentivize gaming it. Winner-take-all politics and business have the highest stakes and therefore the highest incentive for gaming but you still see intense gaming even in things that everybody should agree on, like education.
posted by Skwirl at 10:00 AM on November 25, 2013 [7 favorites]


Well, this does prove scientists understand nothing about human nature.

"You have to understand: we are really not sure about any of this" is fairly useless info. Politics is struggle; science is in charge of ammunition manufacture. However unreliable your estimates as to the size of the crater generated, the bomb will still be thrown, because anything that can damage the other side or advance your own is of use.

I love the airy sniff at the beginning, too. Of course, scientists are to busy to get involved in your mud slinging. Nevertheless, we would like to inform you that you are doing it all wrong. Good gravy.

I mean, in some senses, it is of course deplorable that humanity is not more rational and not more willing to embrace prudence and caution before launching a new policy regime on limited evidence. But, scientists, get it through your thick skulls: humanity is not more rational. And we will all grow old and grey before we have perfect certainty about any complex topic, and in the meantime there are kids to be educated and economies to be run and budgets to be made and we have to decide on the best way to do these things.
posted by Diablevert at 10:06 AM on November 25, 2013 [6 favorites]


The P-value is the probability of observing an outcome at least as extreme as the one observed, assuming the null hypothesis is true

Even worse, it's the probability of observing an outcome at least as extreme as the one observed if a specific counterfactual data-generating process implied by the null hypothesis were true.
posted by ROU_Xenophobe at 10:06 AM on November 25, 2013 [5 favorites]


in the meantime there are kids to be educated and economies to be run and budgets to be made and we have to decide on the best way to do these things.

Knowing how sure we are about certain things is important to know when setting policy, too.

There's a big difference between setting policy based on, say, maxwells laws and a psychological study which has never been reproduced.
posted by empath at 10:15 AM on November 25, 2013


There's a big difference between setting policy based on, say, maxwells laws and a psychological study which has never been reproduced.

There's a big difference in how likely the policy is to be effective. There's not a big difference in how likely the policy is to be enacted. That's the problem with the article, it seems to think stupid policies get passed because people ignorantly but rationally believe they will be effective, and if you could lessen people's ignorance about how science works, they wouldn't pass stupid policies. But a whole hell of a lot of stupid policies get passed because people ignorantly and irrationally believe they will be effective, and you've got to fight irrationality with irrationality --- with a better story, or an appeal to a baser need.
posted by Diablevert at 10:41 AM on November 25, 2013


I'm sorry, but that is cynical and stupid in equal measure.
posted by empath at 10:51 AM on November 25, 2013


I think Diablevert is not being stupid or cynical. I used to work writing policy documents for government - I crafted the text, in general other people set the policy direction. The original article is naive. Policy makers are not trying earnestly to use scientific studies to guide them. Rather they have entirely different priorities.

In general there is a groundswell of policy opinion - maybe among the general public, maybe in a key group such as donors or party members - in favour of a particular action. In addition there is ministerial prejudice (about what will work, about what 'the public' will support). The demand is then to find evidence which supports that action.

There will be a range of voices among advisors. In general those who support the ministerial preference will win out, and most other people will see it as intelligent to get on this bandwagon. Occasionally other issues will be significant, and overwhelming scientific consensus - as in the case of global warming - will in some cases begin to turn the massive ship of public opinion.

But really the theoretical issues mentioned in the article are understood by almost all highly educated people, and senior civil servants are generally very well educated. However they are working in fraught and pressured circumstances, with people ready to stab them in the back at all times.
posted by communicator at 11:16 AM on November 25, 2013 [2 favorites]


I just want to follow up. I think the misunderstanding here is a very significant one. People with scientific training have insufficient respect for other forms of intellect. I can completely understand why people might find scientific inference and statistical prediction the most valuable and respectable of skills. However, they should understand that there are people just as bright as they are who use their intellect in quite different ways - to negotiate complex social hierarchies for example.

Scientists may say 'but scientific reasoning gets results'. Negotiators would say, no we get results, that is why we have got more money and power. Both types of people are using their high intelligence to achieve the ends that they desire.

I am neither type of person, not as clever as either, more a sort of mediator between the two worlds. I think scientists have a better understanding of physical reality, and negotiators have the greater ability to understand the social reality. This article is an example of failure by scientists to understand and model social reality.
posted by communicator at 11:25 AM on November 25, 2013 [6 favorites]




That's a great summary of what to look for in studies/claims/reports. And I never came across anything like that in undergrad and a year of grad stats courses. It is concise and succinct; props.

I see general news and articles from a variety of sources in the media constantly that will say things generically like, "A study from the University of _____ shows that ______." No citations or references to the study.

So of course, the first thing to say is always: "Show me the data!"
posted by CrowGoat at 12:57 PM on November 25, 2013


> I mean, in some senses, it is of course deplorable that humanity is not more rational and not more willing to embrace prudence and caution before launching a new policy regime on limited evidence. But, scientists, get it through your thick skulls: humanity is not more rational. And we will all grow old and grey before we have perfect certainty about any complex topic, and in the meantime there are kids to be educated and economies to be run and budgets to be made and we have to decide on the best way to do these things.

Yes, speed is a factor in info gathering, as in all human endeavors. We could get great information given unlimited time, but we do not have unlimited time, so we need to make decisions based on imperfect information.

I think scientists are basically aware of this, though, right? So how exactly would you like them to act differently? Your comment seems very vehemently in favor of getting scientists to significantly change something about how they do things ("get it through your thick skulls!"). But change what, exactly? I admit I am confused.
posted by officer_fred at 1:32 PM on November 25, 2013


Your comment seems very vehemently in favor of getting scientists to significantly change something about how they do things ("get it through your thick skulls!"). But change what, exactly? I admit I am confused.

Accept that no amount of fussbudgeting will get people to stop "misusing science" by overstating claims. This is not a problem you can fix by tsking, which is what this paper is.

I had a longer rant here, but that's the gist. I think what made me lose my temper was the bit at the beginning where they state as a premise that of course, real scientists are far too busy to engage in public debate in a way that could influence it. Science is hard and scientist are busy people, and that's fair enough. If you can't be buggered to descend from Olympus that's your lookout, but you're certainly not accomplishing much by blue-tacking a note about how to interpret statistical data to the base of the mountain.
posted by Diablevert at 2:20 PM on November 25, 2013 [1 favorite]


Would it be fair to say that your main point is just that scientists should generally act and speak in a more humble way, and claim less high status for themselves? It seems like your objections to them have little do do with the specific debate of how should science influence public policy, and a lot to do with their overall arrogance (which is egregious, I agree).
posted by officer_fred at 2:49 PM on November 25, 2013


Would it be fair to say that your main point is just that scientists should generally act and speak in a more humble way, and claim less high status for themselves? It seems like your objections to them have little do do with the specific debate of how should science influence public policy, and a lot to do with their overall arrogance (which is egregious, I agree).

Aw, c'mon, man, you're being so reasonable and temperate you force me to do the same, and I was really working on my Malcolm Tucker manqué impression.

I would say that my main objection is not to arrogance, but to blinkeredness. Arrogance rules me up, but what's really frustrating about a paper like this is that it's useless. It's a ref's handbook for Calvinball. There are reasons why politics works the way it does, reasons to do with human nature and human need. One cannot stand outside politics and complain that it misuses science because it does not use science as science does; politics uses (and abuses) science for entirely different purposes. So no matter how slowly and how patiently you explain the rules of science you will not succeed in turning politicians into scientists, nor preventing them from using science for their ends. Politics may not be a game that scientists wish to play, themselves; but they can't dictate the play from the stands.
posted by Diablevert at 3:08 PM on November 25, 2013 [2 favorites]


What scientists can do:

Hire more lobbyists. The Union of Concerned Scientists is a good start, but they are a lightweight at the end of the day. And dang, you can say almost whatever you want when you have tenure. That has got to be worth something.

There are days where, as a low level office drone, I wish I could call office hours and say, "Hey Mr. Professor Man, my leadership thinks X but could be swayed towards Y. Which is more crackheaded, X or Y?"

And STOP SUBMITTING SCIENCE TO PROPRIETARY JOURNALS LIKE IT'S STILL A CENTURY WHERE SPREADING INFORMATION COSTS MONEY. I needed to bone up on public housing outcomes, so I go to the Library of Congress thinking, hey, if anywhere needs access to research on public housing outcomes and effects, it's Congress, right? Nope -- they only subscribe to the relevant journals archives from the 80s or earlier. Thanks proprietary science that I probably funded with tax or tuition dollars at some point.

Wanna know why I always cite think tanks? 'Cuz I can actually access their writing right now without begging my boss for a budget that I will never get no matter how little I ask for. You think grunt work congressional aides who scrape by in one of the most expensive cities in America on retail wages can afford articles at $12-40 a pop? Yeah, no, they're Googling think tanks if you're lucky, but probably mostly Wikipedia, blogs and cable news sites.
posted by Skwirl at 3:10 PM on November 25, 2013 [2 favorites]


> One cannot stand outside politics and complain that it misuses science because it does not use science as science does; politics uses (and abuses) science for entirely different purposes.

That makes sense. So that makes me curious. How do you, personally:

1. Decide on your political beliefs,

2. Check whether you are making a mistake,

3. Attempt to implement your goals, by persuasion or other means,

If not using scientific methods?
posted by officer_fred at 3:23 PM on November 25, 2013 [1 favorite]


And STOP SUBMITTING SCIENCE TO PROPRIETARY JOURNALS LIKE IT'S STILL A CENTURY WHERE SPREADING INFORMATION COSTS MONEY. I needed to bone up on public housing outcomes, so I go to the Library of Congress thinking, hey, if anywhere needs access to research on public housing outcomes and effects, it's Congress, right? Nope -- they only subscribe to the relevant journals archives from the 80s or earlier. Thanks proprietary science that I probably funded with tax or tuition dollars at some point.

This is one of the things that, like Diablevert, really pisses me off about the hand washing anti-politics claim at the start of this. By participating in the academic system you're committing to a political action that has consequences. There's no profession that gets to shrug and say it doesn't play politics - they all do. They address this a bit here:

Scientists are human. Scientists have a vested interest in promoting their work, often for status and further research funding, although sometimes for direct financial gain. This can lead to selective reporting of results and occasionally, exaggeration. Peer review is not infallible: journal editors might favour positive findings and newsworthiness. Multiple, independent sources of evidence and replication are much more convincing.
posted by codacorolla at 9:20 PM on November 25, 2013


So that makes me curious. How do you, personally:

1. Decide on your political beliefs,

2. Check whether you are making a mistake,

3. Attempt to implement your goals, by persuasion or other means,

If not using scientific methods?


Temperament, experience, instinct, rhetoric.

My personal feeling is that most people's politics are more temperament than anything else, temperament shaped by lived experience. The fundamental divide between right and left, I tend to think, is whether one views a person's life as fundamentally shaped by internal or external forces. People drawn to the right tend to believe the former: a person's destiny is under their control, subject to their will and effort, and though they may face external obstacles if they have sufficient internal strength those obstacles will be overcome, and with sufficient diligence anyone may succeed. People drawn to the left tend to believe the latter, that the circumstances in which we are born and grow up do a great deal to shape us, that in the right soil any seed may blossom and in a desert none can. Those two basic outlooks on the world, I think, occur in many cultures, it's more a tendancy of mind, like being musical or red-headed than a willful choice. But it shapes all politics.

If forced to self-diagnos my own temperament, I'd say I'm both fairly liberal and fairly cynical. A believer in the ability of external forces to shape our ends, a pessimist as to our ability to change those forces. (Overlaying this belief is the belief that while Stuff Changes, People Don't Change; i.e. that technological changes do far more to change culture than culture does to change itself, or to put it another way, culture itself is a response to its constraints.)

Bearing all that in mind, my practical political beliefs tend to be fairly liberal and fairly pragmatic. In favor of the government doing things that will improve people's circumstances, generally okay with half-a-loaf compromises, usually skeptical of anybody's ability to move mountains. Try and keep aware that corruption and fuckups will occur on my side as well as my opponents and weigh whether the risk and cost of them is sufficient to warrant opposing a seemingly good idea.

Beyond that, as to two, I have little to offer you but platitudes. I worry I may rely on my innate contrariness to alert me to the weakness in my side's arguments when I hear them voiced. Listening to someone make a case for white almost always makes me think of the black side of view, even on the whole I'm on the white's side of the fence.

As for three, in politics what other means are there but persuasion and force? I'm not much for force, myself. Science, of course, falls under persuasion. It's always nice to have the evidence on your side, beats the law and banging on the table --- most of the time.*


*"and if I were disposed to stir your hearts and minds to mutiny and war, I would do Brutus wrong, and Cassius wrong, and they are both, both honourable men."
posted by Diablevert at 9:36 PM on November 25, 2013


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