Sensitivity and specificity are prevalence-independent test characteristics, as their values are intrinsic to the test and do not depend on the disease prevalence in the population of interest. Thanks! (true positives + true negatives)/total test results = (TP+TN)/(TP+TN+FP+FN). Figure 4. If 100 with no disease are tested and 96 return a completely negative result, then the test has 96% specificity. The equation to calculate the sensitivity of a diagnostic test The specificity is calculated as the number of non-diseased correctly classified divided by … Positive and negative predictive values, but not sensitivity or specificity, are values influenced by the prevalence of disease in the population that is being tested. Specificity calculator to evaluate the chances of a person being affected with diseases, calculated based on the present health conditions. Accuracy, or efficiency, is the percentage of test results correctly identified by the test, i.e. In medical diagnosis, test sensitivity is the ability of a test to correctly identify those with the disease (true positive rate), whereas test specificity is the ability of the test to correctly identify those without the disease (true negative rate). Example of Sensitivity and specificity. If 100 patients known to have a disease were tested, and 43 test positive, then the test has 43% sensitivity. Assumption: You have a new rapid diagnostic test being evaluated for the screening of COVID-19, on the specific antibodies produces against the virus, SARS-CoV-2. Negative cases are classified as true negatives (healthy people correctly identified as healthy) whereas false negative (sick people incorrectly identified as healthy). In other words, the sensitivity is the proportion of diseased individuals correctly classified, and that's 80% in this case. These concepts are illustrated graphically in this applet Bayesian clinical diagnostic model which show the positive and negative predictive values as a function of the prevalence, the sensitivity and specificity. Helpful 0 Not Helpful 0