Test Positive | Test Negative | |
Disease Present | True Positive (TP) | False Negative (FN) |
Disease Absent | False Positive (FP) | True Negative (TN) |
SENSITIVITY:
Sensitivity of a test is the percentage of all patients with disease present who have a positive test.
__TP___ X 100 = Sensitivity (%)
TP + FN
SPECIFICITY:
Specificity of a test is the percentage of all patients without disease who have a negative test.
__TN___ X 100 = Specificity (%)
FP + TN
PREDICTIVE VALUE:
The predictive value of a test is a measure (%) of the times that the value (positive or negative) is the true value, i.e. the percent of all positive tests that are true positives is the Positive Predictive Value.
__TP___ X 100 = Predictive Value of a Positive Result (%)
TP + FP
__TN___ X 100 = Predictive Value Negative Result (%)
FN + TN
TEST EFFICIENCY:
The efficiency of a test is the percentage of the times that the test give the correct answer compared to the total number of tests.