I was always taught that psychology is about the description and prediction of behavior. Description? Easy. I can do that! Prediction? Well, er….not so fast. But isn’t description also prediction? If I say that John has an IQ of 100, it is clearly a description, subject of course to a whole bunch of caveats based on reliability, validity, generalizability, confidence intervals, etc. If we want to be conservative about it, we could say, using a norm-referenced interpretation, John’s score on the IQ test of 100 falls at the numerical mean for the reference group. Beyond that it starts getting difficult. Isn’t my statement about John also a prediction? That it addresses how John is likely to behave under certain conditions? I would enjoy hearing from people on this, since assessment psychologists are doing this sort of thing everyday. We will get to the really juicy issue, whether psychologists can predict future violence, later…
