Annette I agree with other answers that you have seen for your technical questions but want to add something to the answers for the question about using the terms independent and dependent variable in correlational studies. Like others I prefer to use the terms predictor and criterion variables in these designs and I teach my students this usage. However, SPSS fosters the use of the terms IV and DV in their multiple regression procedure where the text box for the predictor variables is labeled "Independent(s)" and the text box for the criterion variable is labeled "Dependent." It is one of the few procedures in SPSS that uses these terms. This mismatch forces me to spend a few extra minutes telling students why the programmers at SPSS might have used those terms and then identifying the appropriate parallels.
Dennis Dennis M. Goff Chair, Department of Psychology Professor of Psychology Randolph College (Founded as Randolph-Macon Woman's College in 1891) Lynchburg VA 24503 [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Sunday, September 07, 2008 4:16 PM To: Teaching in the Psychological Sciences (TIPS) Subject: [tips] Several questions (1) I talk with my intro students about the misconception that mentally ill people generally have a history of violence. And the research evidence seems to support this. But in thinking about where the misconception comes from, would it not be correct to say that most people with a history of violence have had a mental illness? In other words, could one be violent or have unmotivated violence and not be mentally ill? A more technical set of questions (1) Is it proper to talk about independent and dependent variables in a correlational study? And to what extent? Isn't it *more* correct to call the variables predictor and criterion variables?What is the current status of this language? (2) I have learned that a rule of thumb for evaluating the effect size of a significant correlation is to square r and this is a crude indicator of how much of the variability in the criterion variable comes from the predictor variable. I'd like to hear if this is too crude to be useable. Is there another, readily calculable effect size? I am very bothered by studies that make a big deal of a significant correlation of .2 or .3. Thanks Annette Annette Kujawski Taylor, Ph.D. Professor of Psychology University of San Diego 5998 Alcala Park San Diego, CA 92110 619-260-4006 [EMAIL PROTECTED] --- To make changes to your subscription contact: Bill Southerly ([EMAIL PROTECTED]) --- To make changes to your subscription contact: Bill Southerly ([EMAIL PROTECTED])
