[EMAIL PROTECTED] (David C. Howell) wrote in message news:<[EMAIL PROTECTED]>... > To Edstat-L list: > > I was asked a question this morning that I can't answer (hardly a new > experience). It may be that the answer is obvious and that I just can't see > it, or that it is a question that does not have an easy answer. > > It is well known how to test the difference between correlations in two > independent samples. It is also well known how to test the difference > between r(xy) and r(xz) by taking into account the correlation between y > and z. But what about the correlation between xy and time 1 and xy at time > 2? Presumably we need to take into account the lack of independence between > Time 1 and Time 2, which means the correlation between x1 and x2 and the > correlation between y1 and y2. > > Can anyone tell me how to go about this? Am I just being blind?
You want the Pearson-Filon test. See Jim Steiger's 1980 Psych.Bull paper. David Kenny's 1987 book also covers it, but there is a mistake in the formula on p.280: the denominator should have Q/(1-r^2)^2, not Q(1-r^2)^2. . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
