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 ...

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 ...

Objective To produce a best evidence synthesis of the clinical effects of topical glyceryl trinitrate (GTN) in the treatment of tendinopathies. Design A systematic review of published randomised ...