Chapter Seven

Gold Standard

also known as the true measure

Selective Screening

is the type of screening applied to high risk groups such as those at risk for STIs. Selective screening is likely to result in the greatest yield of true cases and to be the most economically efficient . Screening tests need to demonstrate reliability and validity.

Reliability (Precision)

refers to the ability of a measuring instrument to give consistent results on repeated trials.

Mass Screening

refers to the application of screening tests to total populations, groups, regardless of their risk status.

Validity (Accuracy)

the ability of the measuring instrument to give a true measure of the entity being measured.

Sensitivity

the ability of the test to identify correctly all screened individuals who actually have the disease. Sensitivity=true positives divided by the sum of true positives and false negatives

Specificity

the ability of the test to identify only non-diseased individuals who actually do not have the disease. Specificity= true negative divided by the sum of true negatives and false positives.

Screening for Disease

the presumptive identification of recognized disease or defects by the application of tasks, examinations or other procedures that can be applied rapidly.

Predictive Value (-)

the proportion of individuals screened negative by the test who actually do not have the disease.

Predictive Value (+)

the proportion of individuals screened positive by the test who actually have the disease.