Marc: Sorry I left the punchline off my previous post. As far as what to tell students: SPSS is "wrong" in that it takes short cuts (I assume that is what it does). But, the short cut methods are closer to the spirit of the way these measures are used in actually practice. -- --------------------------------------------------------------- John W. Kulig [EMAIL PROTECTED] Department of Psychology http://oz.plymouth.edu/~kulig Plymouth State College tel: (603) 535-2468 Plymouth NH USA 03264 fax: (603) 535-2412 --------------------------------------------------------------- "What a man often sees he does not wonder at, although he knows not why it happens; if something occurs which he has not seen before, he thinks it is a marvel" - Cicero.