title: Known versus unknown threats to internal validity: a response to Edwards.
authors.affiliation: Department of Psychology, New Mexico State University, MSC 3452, P.O. Box 30001, Las Cruces, NM 88003-8001, USA. sc_rice@yahoo.com
authors.forename: Stephen
authors.initials: S
authors.lastname: Rice
authors.forename: David
authors.initials: D
authors.lastname: Trafimow
mesh_terms: D002986:Clinical Trials as Topic / Q000941:ethics / Q000592:standards; D032982:Contracts / Q000941:ethics / Q000331:legislation & jurisprudence; D006801:Humans; D010352:Patient Dropouts / Q000331:legislation & jurisprudence; D015203:Reproducibility of Results; D012108:Research Personnel / Q000941:ethics; D035842:Research Subjects / Q000331:legislation & jurisprudence; D014838:Volunteers / Q000331:legislation & jurisprudence