An indicator is said to valid if
Ans) b (It measures the thing.. ) Ref park 20th ed p 226The term validity refers to what extent the test accurately measures which it purports/ intended to measure.Validity expresses the ability of a test to separate or distinguish those who have the disease from those who do not have.Validity has two components - Sensitivity and specificitySensitivity and specificity together with "predictive accuracy" are inherent properties of a screening test.
It also measures the thing it didn't suppose to measure
It measures the thing it expected to measure
Over value when measured by different method
Under value when measured by different method
Biostatistics