Validity: the extent to which measurements reflect the true values of the theoretical factors that the observed variable is supposed to measure Sensitivity: proportion of people labelled positive by the test among those with the disease Specificity: proportion of people labelled negative by the test among those without the disease . Predictive value (+): proportion of people who tested positive who have the disease . Predictive value (-): proportion of people who tested negative among those without the disease Formulae: Sensitivity = a/a+c . Specificity = d/b+d . PPV = a/a+b . NPV = d/c+d . False Positive = b/b+d . False Negative = cla+c . Disease prevalence = a+c / a+b+c+dErrors of Measurement The following are hypothetical results of a study comparing performance of a newly developed rapid antibody test for COVID-19 as compared to real-time reverse transcription polymerase chain reaction (rRT-PCR). rRT-PCR Test result Rapid Antibody Test Total ( + ) ( - ) Positive 142 36 178 Negative 18 122 140 Total 160 158 318Compute the following (show the formula and solution) 1. Prevalence = 2. Sensitivity = 3. Specificity = 4. PPV = 5. NPV = 6. FP = 7. FN =