Nowhere is the challenge of getting people to understand how to use data better illustrated than the methodology wars being fought in the discipline of Psychology. If you haven’t heard of the methodology wars be assured that the battlefields – studies in psychological research – are being fought over like blocks of Stalingrad; and like that famous battle, not much is left standing in the aftermath.
I’m not sure exactly how the methodology wars started. Somehow, somewhere, someone decided to actually re-test a “classic” study in psychology. A study that’s been accepted into the core of the discipline – that established somebody’s reputation, made somebody a career. Only it didn’t replicate. They re-did the experiment as carefully as they could and it didn’t show the same result. Didn’t, usually, show any result at all. Increase the sample size to fix the problem and the signal becomes even clearer. Alas, the signal always seems to be that there is no signal.
Pretty soon people started calling into question nearly every Psych study done over the last fifty years and testing them. And many – and I mean many – have failed.
Slate’s article (and it’s really good – giving a great overview of the issue – so give it a read) recounts the latest block to burn down in psychology’s methodology wars. The research in question centered around the idea that our facial states feedback into our emotions. If we smile (even inadvertently) we will feel happier.
It’s an interesting idea – intuitively plausible – and apparently widely supported by a huge variety of studies in the field. It’s an idea which strikes me as perfectly reasonable and in which I have zero vested interested one way or another.
But when it was submitted to rigorous simultaneous validation in a number of different labs, it failed. Completely.
The original test involved 32 participants and a change in average subjective scoring between the two groups of 4.4 to 5.5. That means each group had sixteen participants. The improved second test had 92 total participants and showed a scoring difference of 4.3 to 51.
That’s a pretty small sample.
Especially for something that became received wisdom. A classic.
So how would people react if it turned out to be wrong?
Well, the Slate article answers that question pretty definitively. Because when the multi-lab tests came back, here’s what happened. Seventeen different labs replicated the experiment with nearly 2000 subjects. In half the participating labs, participants who smiled recorded a slightly higher average on the resulting happiness test (but much lower than in the original experiment). In the other half, it went the other way.
Net, net, there was no correlation at all. Zero.
Okay, so far you have just another sad story of a small sample size failure.
That’s not what really attracted my attention. Nope. What really made me laugh in utter disbelief was the comment of the “scientist” who had done the original research. Here it is, and I quote in full lest you think I’m about to exaggerate:
“Fritz Strack has no regrets about the RRR, but then again, he doesn’t take its findings all that seriously. “I don’t see what we’ve learned,” he said.
Two years ago, while the replication of his work was underway, Strack wrote a takedown of the skeptics’ project with the social psychologist Wolfgang Stroebe. Their piece, called “The Alleged Crisis and the Illusion of Exact Replication,” argued that efforts like the RRR reflect an “epistemological misunderstanding,” since it’s impossible to make a perfect copy of an old experiment. People change, times change, and cultures change, they said. No social psychologist ever steps in the same river twice. Even if a study could be reproduced, they added, a negative result wouldn’t be that interesting, because it wouldn’t explain why the replication didn’t work.
So when Strack looks at the recent data he sees not a total failure but a set of mixed results. Nine labs found the pen-in-mouth effect going in the right direction. Eight labs found the opposite. Instead of averaging these together to get a zero effect, why not try to figure out how the two groups might have differed? Maybe there’s a reason why half the labs could not elicit the effect.”
[Bolding is mine]
So here’s a “scientist” who, despite presumably being familiar with the extensive literature on statistics and the methodology wars, somehow believes that because half the labs reported a number slightly above average the key thing to look at is why the other half didn’t. Apparently, the only thing that would satisfy him is if all the labs reported an exactly opposite result. Which, presumably, would result in a new classic paper that frowning makes you happier!
It’s random variation calling for you, Dr. Strack!
Cause here’s the thing…you’d expect about half the labs to show a positive result when there is no correlation. If some labs didn’t report a positive result then the correlation would pretty much have to be negative, right?
This isn’t, as he appears to believe, half-corroboration. It’s the way every null result ever found actually looks out here in the real world. I’d advise him to try flipping a coin 100 times, repeatedly, and see how often it comes out 50 heads and 50 tails. He might be surprised to learn that about the half the time this test will yield more heads flips than tail flips. This does not mean that heads is more likely than tails and it does not suggest that researchers should focus on why some trials yielded more heads and other trials yielded more tails.
Okay, I get it. You published a study. You made a career out of it. It’s embarrassing that it turns out to be wrong. But it’s hard to know in this case which is the worse response – intellectual dishonesty or sheer stupidity. Frankly, I think the latter. Because I don’t care how dishonest you are, some explanations should be too embarrassing to try on for size. And the idea that the right interpretation of these results would be to look for why some labs had slightly different results than others clearly belongs in that category.
I find the defense based on the difficulties of true replication more respectable. And yet, what are we to make of an experiment so delicate that it can’t be replicated AT ALL even with the most careful controls? How important can any inference we make from such an experiment plausibly be? By definition, it could only fit the most narrow range of cases imaginable. And the idea that replication of an experiment doesn’t matter seems…you know…a tad unscientific.
From my perspective, it isn’t the original study that illustrates the extraordinary problem we have getting people to use data well. Yes, over-reliance on small sample sizes is all too common and all too easy. That’s unfortunate, not shameful. But the deeper problem is that even when data is used well, a lethal combination of self-interest and a near total lack of understanding of basic statistics make it all too possible for people to ignore the data whenever they wish.
As Simon and Garfunkel plaintively observed, “A man hears what he wants to hear, and disregards the rest”.
If it wasn’t so sad, it would be funny.
Dammit. It is funny.
For it’s easy to see that in this version of the psych methodology wars, the defenders have their own unique version of a foxhole – with posterior high in the air and head firmly planted in the sand.