title: Internal validity.
authors.affiliation: Colorado State University, Fort Collins, USA.
authors.forename: G A
authors.initials: GA
authors.lastname: Morgan
authors.forename: J A
authors.initials: JA
authors.lastname: Gliner
authors.forename: R J
authors.initials: RJ
authors.lastname: Harmon
mesh_terms: D015982:Bias; D003627:Data Interpretation, Statistical; D006805:Human Experimentation; D006801:Humans; D015203:Reproducibility of Results