Translations:Advanced Field Epi:Manual 2 - Diagnostic Tests/138/en
Estimation of true prevalence from apparent prevalence
When we apply a test in a population, the proportion of positive results observed is the apparent prevalence. However, depending on test performance, apparent prevalence may not be a good indicator of the true level of disease in the population (the true prevalence). However, if we can estimate the sensitivity and specificity of the test, we can also estimate the true prevalence from the apparent (test-positive) prevalence (AP) using the formula ([#16 Rogan and Gladen, 1978]):