I respectfully disagree with much of what you have said, Mike, and probably because I come from a cognitive perspective where almost everything I do is repeated measures. Most of the threats to internal validity that you have noted are not a problem with the type of research that I do, as long as I have good counterbalancing or randomized presentation of conditions. AND, I have the advantage of reduced error and a need for fewer participants. And I do believe that despite the lack of random assignment to groups ( which in the case of repeated measures is a nonsense), that I still have a true "experiment".
However, I think we are getting far afield from the original posting in which, as I recall, a student compared groups based on survey responses and called it an experiment...... Annette Quoting Mike Scoles <[EMAIL PROTECTED]>: > I'm going to stick with Sir Fisher and reserve the term "experiment" for > situations where there is random assignment to conditions. I do not know of > any within-subjects designs that would not be better as mixed designs. > Within-subject designs are too easily compromised by history, maturation, > instrumentation, attrition, and (sometimes) test sensitization and > regression issues. Let's see, the only one of the "Big 7" that I left out > was subject selection--the major problem with quasi-experiments. Of course, > good quasi-experiments can provide information as useful as a marginal > experiment. > > Notice that many texts discuss quasi-experiments and single-subject designs > in the same context. Even though many people would consider single-subject > designs to be true experiments, they have many of the same flaws as > quasi-experiments. These flaws can be minimized by careful attention to > control of extraneous variables, but that doesn't make them true experiments > in Fisher's sense. > > ************************************************* > Michael T. Scoles, Ph.D. > Director, Arkansas Charter School Resource Center > Associate Professor of Psychology & Counseling > University of Central Arkansas > Conway, AR 72035 > voice: (501) 450-5418 > fax: (501) 450-5424 > ************************************************* > > > > --- > You are currently subscribed to tips as: [EMAIL PROTECTED] > To unsubscribe send a blank email to [EMAIL PROTECTED] > Annette Kujawski Taylor, Ph. D. Department of Psychology University of San Diego 5998 Alcala Park San Diego, CA 92110 [EMAIL PROTECTED] --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
