Diagnostic Test Calculator

The diagnostic test evaluation is a method to evaluate the chances of being affected with diseases, calculated based on the present health conditions. In the below Diagnostic Test Calculator, enter the values for the true positive and false negative values for Disease Present category and False positive and true negative for disease absent category and click calculate to evaluate the medical diagnosis factors such as Sensitivity, Specificity and other values.

Medical Diagnosis Evaluation | Calculator for Sensitivity

Disease
TestPresentAbsentTotal
PositiveTrue Positive False Positive
NegativeFalse Negative True Negative
Total
%
%
%
%
%
%
%
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Formula:

Sensitivity = a / (a + b) x 100 Specificity = c / (d + c) x 100 Positive Likelihood Ratio = (Sensitivity / 100) / (1-(Specificity / 100)) Negative Likelihood Ratio = (1- (Sensitivity / 100)) / (Specificity / 100) Disease Prevalence = (a + b) / (a + b + d + c) x 100 Positive Predictive Value = Sensitivity / (Sensitivity + d) x 100 Negative Predictive Value = c / (b + c) x 100
Where, a = True Positive b = False Negative c = True Negative d = False Positive

Example

When a patient have disease number with true positive value of 10, false negative value of 5, non disease number with false positive value of 40 and true negative value of 45. His/her medical diagnostic test evaluation will be as follows,

Sensitivity = 10 / (10 + 5) x 100
= 66.67%
Specificity = 45 / (40 + 45) x 100
= 52.95
Positive Likelihood Ratio = (66.67 / 100) / (1-(52.9 / 100))
= 1.42%
Negative Likelihood Ratio = (1- (66.67 / 100)) / (52.9 / 100)
= 0.63
Disease Prevalence = (10 + 5) / (10 + 5 + 40 + 45) x 100
= 15%
Positive Predictive Value = 66.67 / (66.67 + 40) x 100
= 20%
Negative Predictive Value = 45 / (5 + 45) x 100
= 90%

Note :This statistics calculator is presented for your own personal use and is to be used as a guide only. Medical and other decisions should NOT be based on the results of this calculator. Although this calculator has been tested, we cannot guarantee the accuracy of its calculations or results.

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