Perfect validity requires that there be no measurement error,therefore:
(XO = XT,XR = 0,XS = 0).

Question

Quizplus · Accepted Answer

Perfect validity means that the measured variable completely represents what it is supposed to represent without any measurement error. Therefore, there should be no systematic error (XR = 0) or random error (XS = 0) in the measurement process, and the observed scores (XO) should be equal to the true scores (XT).

Perfect Validity Requires That There Be No Measurement Error,therefore