The maturation threat can operate when biological or psychological changes occur within subjects and these changes may account in part or in total for effects discerned in the study. For example, a ...

There is a distinction that one learns about on the first day of a course in psychological research methods. It is the difference between internal and external validity. Internal validity is ...

Although problems with internal validity are typically associated with studies reporting statistically significant differences, methodological problems may introduce extraneous variance into the study ...