For ADC examination, both prelims and practical viva voce, and NEET MDS, the various measures of evaluating a screening test must be known to the students.
There are various measures to evaluate a screening test that are as follows:
- Positive predictive value
- Negative predictive value
Sensitivity: Sensitivity is defined as the ability of a test to identify correctly all those who have the disease i.e. “true positive”.
Specificity: Specificity is the ability of a test to identify correctly those who do not have the disease i.e. “true negatives”
Predictive value: Besides sensitivity and specificity, the performance of a screening test is measured by its “predictive value”. The predictive value tells us about the diagnostic power of the test. The predictive value of a positive test indicates the probability a patient with a positive test result has , in fact, the disease in question. As the prevalence of a disease in a given population increases, the accuracy of the predictive value of a positive test increases.
Yield: Yield is the amount of the previously unrecognized disease that is diagnosed as a result of the screening efforts.