Selection bias

Who shows up for experiments?

Peer nominations of pathological personality traits were collected on
1442 freshmen participating in a study regarding personality and 283
students who initially provided consent to participate but failed to
show up for the assessment.  Ten peer-based personality disorder scales
and eight IIP-64 scales were entered into two separate multiple
logistic regression procedures to predict the probability of
nonparticipation.  There was a significantly higher probability of
participation if peers nominated someone as having more histrionic,
obsessive–compulsive, self-sacrificing, and intrusive/needy
characteristics.  Students were significantly less likely to participate
if peers nominated them as being higher on narcissism or
non-assertiveness.  Results suggest it may be more difficult to obtain
sufficient numbers of people high in narcissistic traits than
individuals with other personality traits.  Researchers may need to
employ novel strategies to recruit individuals with narcissistic traits
for experimental studies.

By the way, I’ve never showed up for any experiments.  I would think the procedure also discriminates against the anti-social, a trait which may be to some extent correlated with narcissism.

The link is from BPS Digest, which also informs us that people born in late winter are smarter; I can only imagine how smart tall, left-handed people, born in late winter [alas, I am not tall], must be…


I loved showing up for experiments, when to donzens of them, mainly because I concidered it my personal mission to goof with them. Every once in a while I could spot a flaw in the experiment, and then I would exploit it, without telling the designer. I had one psychology grad student convinced that I had preternatural reactions from fencing, even thought it was really because she had made a simple mistake in generating the slides she wanted me to memorize. In fact, some experimenters even call me back to play the other side of agame just to see what I would do. Naturally, it was the complete opposite of what they expected, if not just plain chaotic.

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