This is probably the wrong question

[redbird]

Someone on my friends list described an odd encounter with a stranger. After posting a comment in which I suggested one possible motivation, I found myself wondering (as we used to when people did harmless but attention-getting things in Freshman Commons [a large dining hall] when I was in college) whether the entire thing was a put-on by a psych student, designed to see how she, and other passers-by, would react.

Then I discarded that, on the grounds that while it could in theory be the explanation for almost anything, it's unlikely, unsatisfying (if only to the story-telling mind), and in this case untestable. And then I found myself wondering, what's the null hypothesis? Presumably not that the entire incident never happened, either that my friend is making this up to see how we react, or that she dreamed or otherwise imagined the encounter. Not the psych student--the percentage of interactions on the streets of any city that are put-ons by psych students is statistically insignificant.

I don't think, in the technical sense of the term, that there is a null hypothesis for the general question "Why did that person do that odd thing?" There probably isn't even a most-likely-guess for the question in general, if only because the set of odd behaviors is so broad, as well as so context-dependent.

Comments

[elynne.livejournal.com]

There is a certain variety of non-standard behavior that I assume to be due to intoxication of one sort or another. However, it is often readily apparant when erratic behavior is a result of intoxication. Strange behaviors that don't have any of the standard intoxication signals... I dunno. I'd love to delve into this further, but I'm going kersplunk. Stupid body.

[brooksmoses]

I'm not sure I've really got a very good understanding of what a null hypothesis is in the general sense. (And so I'll take this opportunity to ask....)

In the introduction to statistics and experimental design class that I had in high school, the idea of a null hypothesis was introduced in the context of a statistical "does item A have a correlation with item B" yes/no question -- the null hypothesis is essentially the "false" or "no change" one of the two possible boolean answers, in the context of testing this with a large number of random statistical samples.

The way that this related to engineering experiments -- which were, in my experience, generally of the "we measured the drag coefficient of this airfoil and it's 0.05 plus or minus 5%" sort, where the uncertainty was virtually all the sort of experimental bias error that doesn't show up as variance of the measurements -- wasn't really described, and the teacher sort of gave the impression that she thought all experiments ought to follow this pattern because that's how it was done in her field and that anyone who did it differently was simply wrong, and so I perhaps got a rather more limited impression of its applicability than would be accurate.

If I were to force the "Why did this person do that?" question into the mold I understand null hypotheses in, it would end up with something like "People who do 'that' do not have a statistically different frequency of such-and-so indicator of 'this' motivation from the overall population," for some given indicator of a motivation. Which rather twists the question a bit.

[brooksmoses]

I suppose, in a more general and multivariate study, the null hypothesis is probably "People who do 'that' do not have a statistical correlation with any of the things we've identified as possible reasons."

[redbird]

Your understanding is better than mine, and I think I am badly abusing the terminology.

What I'm groping for, I think, is something between "the most likely reason for behavior X" and "a reason that we should eliminate before guessing wildly." Stated that way, it's silly, since guessing wildly seems to be the core of what I'm doing here.

[purpletigron.livejournal.com]

'Because zie felt like it'?

[carandol.livejournal.com]

Lancaster used to have a couple of very large mental hospitals. These were closed down in the 1980s, and most of the inhabitants were released to "care in the community." Any odd behaviour round here I usually attribute to mental illness. Or drink. Or drugs. And anyway, one culture's odd behaviour is another culture's perfectly normal behaviour. I was reading recently that in Taiwan, walking along eating in the street is considered the height of bad taste, the equivalent of dropping your trousers in public. I do it all the time.