internal validity


validity

 [vah-lid´ĭ-te] the extent to which a measuring device measures what it intends or purports to measure.construct validity the degree to which an instrument measures the characteristic being investigated; the extent to which the conceptual definitions match the operational definitions.content validity verification that the method of measurement actually measures what it is expected to measure; see also face validity.external validity the extent to which study findings can be generalized beyond the sample used in the study.face validity a type of validity" >content validity, determining the suitability of a given instrument as a source of data on the subject under investigation, using common-sense criteria.internal validity the extent to which the effects detected in a study are truly caused by the treatment or exposure in the study sample, rather than being due to other biasing effects of extraneous variables.predictive validity the effectiveness of one set of test or research results as a predictor of the outcome of future experiments or tests.

internal validity

The extent to which differences between the intervention and control groups in a clinical study can be confidently attributed to the intervention and not to an alternative explanation, which requires reducing confounding factors and bias to a minimum. Explanatory clinical studies seek to maximise internal validity by rigorous control of all variables—e.g., age, sex, co-morbidities—other than the intervention itself.