[From Bill Powers (950225.1245 MST)]
Bruce Abbott [950225.1245 EST] --
Would someone tell me what the phrase "controlling for" is supposed
to mean?
You just about answered the question yourself, by saying
Just trying to control for clarity. ;->
Would you say you are "controlling clarity?" That would imply that you
are doing so successfully -- that your actions are creating clarity in
your perceptions. What you mean is that you are trying to achieve
clarity by using a control process, but by implication that there is
some perhaps considerable degree of error remaining.
When we say we are controlling for x, we are really referring to the
reference level, not the actual state of x. I am controlling for a high
score on a pinball machine, meaning I am using actions that I think will
produce a high score -- whether or not I achieve a high score.
The meaning is also somewhat clearer in a question: "What are you
controlling for?" ("I'm controlling for you being nice to me" or "I'm
controlling for the 6-ball in the side pocket."). You ask the question
when you can see what the other person is doing, but don't know what the
intended consequence is.
I suppose the words "controlling for" are meant to be more explicit than
"achieving" or "hoping for" or "aiming for" or "acting toward." There is
a connotation of perception, reference level, and action in the phrase,
as it seems to be used naturally. The term, incidentally, was invented
by Tom Bourbon's students (or somebody's students -- I forget).
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Best,
Bill P.