Simon, Steve, PhD <[EMAIL PROTECTED]> wrote: : I would not be as critical as some of the others on the list. Sometimes a : categorical variable is easier to interpret. A lot of dietary research, for : example, looks at the highest quintile of fat consumption and compares it to : the lowest quintile. I can visualize those two groups pretty well.
But this is different from dichotomization. Sam Green published a paper a few years ago (I believe it was in Multivariate Behavioral Research) showing that if you use enough categories, say, six or seven, the loss of information is not too bad. : Furthermore, categorization mitigates some of the problems caused by : measurement error. Can you say more about this? My understanding was that by definition, dichotomizing will reduce the reliability of a continuous measure. Mike Babyak Duke University Medical Center . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
