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]
