title: [Evaluation in health interventions: looking for balance between internal validity of results and external validity of conclusions].
authors.forename: Juan
authors.initials: J
authors.lastname: Gérvas
authors.forename: Cristina
authors.initials: C
authors.lastname: Pérez Andrés
mesh_terms: D002986:Clinical Trials as Topic / Q000592:standards*; D006801:Humans; D011634:Public Health / Q000592:standards*; D016032:Randomized Controlled Trials as Topic / Q000592:standards