Table 1.

Test performance parameters (adapted from reference ²⁴).

		Disease
		Positive	Negative
Test Result	Positive	True Positive (TP)	False Positive (FP)
	Negative	False Negative (FN)	True Negative (TN)

Sensitivity = TP / (TP + FN)

Specificity = TN / (TN + FP)

Positive Predictive Value (PPV) = TP / (TP + FP)

Negative Predictive Value (NPV) = TN / (TN + FN)

Likelihood Ratio for Positive Test (LR+) = (TP / (TP +FN)) / (FP /(FP + TN))

Likelihood Ratio for Negative Test (LR−) = (FN / (TP + FN)) / (TN / (FP + TN))

Diagnostic Accuracy = (TP + TN) / (TP+TN+FP+FN)

Pre-test probability (prevalence) = (TP + FN) / (TP+FP+TN+FN)

Pre-test Odds = prevalence / (1-prevalence) = (TP + FN) / (FP + TN)

Post-test Odds = pre-test odds x likelihood ratio

Post-test Probability = post-test odds / (1+ post-test odds)