Scientists across all fields make various types of claims about their innovations. Validity tests check whether they deliver ...

The following discussion is based on the framework of Campbell and Stanley, [1] in that specific threats to establishing a cause-and-effect relationship (i.e., internal validity) are associated with ...

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 ...

When investigators think of generalizability, they typically think of extrapolating the results to other patient populations, depending on whether patients were selected for the study by means of ...