Sensitivity and Specificity
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Disease Prevalence | Interpretation | Value | SE | % Confidence Interval | Null Hypothesis | Z value | P value | ||
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The proportion that people with the disease make out of all persons in the sample. \( DP = \frac{TP+FN}{N} \) | DP | ||||||||
Sensitivity | Interpretation | Value | SE | % Confidence Interval | Null Hypothesis | Z value | P value | ||
The probability that you test positive if you have the disease. It's the same as the power (1 - β) of the test. \( Sensitivity = \frac{TP}{TP+FN} \) | Sensitivity | ||||||||
Specificity | Interpretation | Value | SE | % Confidence Interval | Null Hypothesis | Z value | P value | ||
The probability that you test negative if you don't have the disease. \( Specificity = \frac{TN}{FP+TN} \) | Specificity | ||||||||
Positive Predictive Value | Interpretation | Value | SE | % Confidence Interval | Null Hypothesis | Z value | P value | ||
The probability that you have the disease if you test positive. \( PPV = \frac{TP}{TP+FP} \) | PPV | ||||||||
Negative Predictive Value | Interpretation | Value | SE | % Confidence Interval | Null Hypothesis | Z value | P value | ||
The probability that you don't have the disease if you test negative. \( NPV = \frac{TN}{FN+TN} \) | NPV | ||||||||
Accuracy | Interpretation | Value | SE | % Confidence Interval | Null Hypothesis | Z value | P value | ||
The probability that the test gives the correct answer (either positive or negative) \( A = \frac{TP+TN}{N} \) | Accuracy | ||||||||
False Positive Rate | Interpretation | Value | SE | % Confidence Interval | Null Hypothesis | Z value | P value | ||
The probability that you test positive if you don't have the disease. It's the same as the risk of type 1 error (α). \( FPR = \frac{FP}{FP+TN} \) | FPR | ||||||||
False Negative Rate | Interpretation | Value | SE | % Confidence Interval | Null Hypothesis | Z value | P value | ||
The "miss rate". The probability that you test negative if you have the disease. It's the same as the risk of type 2 error (β). \( FNR = \frac{FN}{TP+FN} \) | FNR | ||||||||
False Discovery Rate | Interpretation | Value | SE | % Confidence Interval | Null Hypothesis | Z value | P value | ||
The probability that you don't have the disease if you test positive. \( FDR = \frac{FP}{TP+FP} \) | FDR | ||||||||
False Omission Rate | Interpretation | Value | SE | % Confidence Interval | Null Hypothesis | Z value | P value | ||
The probability that you have the disease if you test negative. \( FOR = \frac{FN}{FN+TN} \) | FOR |
Positive Likelihood Rate | Interpretation | Value |
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The probability that a person with the disease tests positive divided by the probability that a person without the disease tests positive. If the rate is greater than 1 the test is more likely to give a true positive than a false positive. If the rate is between 0 and 1 the test is more likely to give a false positive than a true positive. \( LR+ = \frac{sensitivity}{1 - specificity} \) | ||
Negative Likelihood Ratio | Interpretation | Value |
The probability that a person with the disease tests negative divided by the probability that a person without the disease tests negative. If the rate is greater than 1 the test is more likely to give a false negative than a true negative. If the rate is between 0 and 1 the test is more likely to give a true negative than a false negative. \( LR- = \frac{1 - sensitivity}{specificity} \) | ||
Diagnostic Odds Ratio | Interpretation | Value |
The rate between the odds of a person testing positive who has the disease relative to the odds of a person testing positive who do not have the disease. \( DOR = \frac{LR+}{LR-} \) | ||
F1 Score | Interpretation | Value |
The F1-score can be used as a single measure of performance of the test for the positive class. It is a measure of the test's accuracy. $$ F_1 = 2 \times \frac{PPV \times Sensitivity}{PPV + Sensitivity} $$ | ||
Power | Interpretation | Value |
The power of the test is the probability that you test positive if you have the disease. It's the same as the sensitivity. \( Power = 1 - \beta = sensitivity \) |