I don't know if this applies specifically to your situation but I do know that the current thinking in statistics is not to use omnibus tests as a hurdle before making more specific comparisons (like in the case of the ANOVA). I would guess the arguments would be similar in the situation you are in so I would say, "go for it!" I will be interested to hear what others have to say.
Rick Dr. Rick Froman, Chair Division of Humanities and Social Sciences Professor of Psychology John Brown University 2000 W. University Siloam Springs, AR 72761 [EMAIL PROTECTED] (479) 524-7295 http://www.jbu.edu/academics/hss/faculty/rfroman.asp "Pete, it's a fool that looks for logic in the chambers of the human heart." - Ulysses Everett McGill -----Original Message----- From: G. Marc Turner [mailto:[EMAIL PROTECTED] Sent: Monday, September 10, 2007 2:01 PM To: Teaching in the Psychological Sciences (TIPS) Subject: [tips] comparing coefficients alpha reliabilities Okay, I'm faced with a problem that I'm hoping someone on the list can provide a better solution to than the one I've come up with so far. I am aware of the W statistic (Feldt, 1969) for testing the difference between 2 coefficient alpha values. Currently, I'm working on some data from a 3x3 design trying to identify which condition(s) produced significantly larger reliability estimates. I could (and actually have) conducted 36 paired comparisons and then adjust the Type I error rate for significance, but I am wondering if there is an extension or alternative that would allow me to do a more omnibus test of the coefficient alpha values prior to the paired comparisons. Additionally, if you know of any measure of effect size you think would be appropriate when discussing the difference between two coefficient alpha values, I'd love to know so I can include it. Any help is greatly appreciated - marc ============================================= G. Marc Turner, PhD, MEd, Network+, MCP Senior Lecturer & Technology Coordinator Department of Psychology Texas State University-San Marcos San Marcos, TX 78666 phone: (512)245-2526 email: [EMAIL PROTECTED] --- ---
