...or why not all the studies in a particular issue of a particular journal? Or all articles written by members of TalkStats? I don't think there's a good answer to this, really. I think the general decision rule applied by many social science researchers is probably "correct for multiple tests when SPSS prompts me to". I think I've heard suggestions that this friendly fellow may be less suspect to this particular problem, though...Lets assume that running more than one test increases the chance of obtaining a type I error. My fundamental question here is what must be the context where the number of tests are counted? An ANOVA? a study? all studies by a researcher? all studies in a day? or all studies?