Validity and Reliability of Tests Flashcards

Vocabulary flashcards covering epidemiological concepts of test validity, reliability, predictive values, sensitivity, specificity, and sources of variation.

Test Validity

The ability of a test to distinguish between who has a disease and who does not.

Sensitivity

The ability of a test to identify correctly those who have the disease, calculated as $\frac{a}{a+c}$ or $\frac{TP}{TP + FN}$.

Specificity

The ability of a test to identify correctly those who do not have the disease, calculated as $\frac{d}{b+d}$ or $\frac{TN}{FP + TN}$.

Gold Standard

The best available test for determining whether a test correctly identifies a disease or condition, characterized by high sensitivity and high specificity.

Dichotomous Test

A screening or diagnostic test whose results are unambiguously either positive or negative.

True Positives

People with the disease who are correctly called positive by the test.

True Negatives

People without the disease who are correctly called negative by the test.

False Positives

People who do not have the disease but are erroneously called positive by the test.

False Negatives

People with the disease who are erroneously called negative by the test.

Sequential Testing

A testing process where follow-up tests are conducted days or weeks later to enhance net sensitivity and net specificity.

Simultaneous Testing

A testing process where multiple tests are administered on the same day or week.

Positive Predictive Value (PPV)

The probability that a patient has the disease given that their test result is positive, calculated as $\frac{TP}{TP + FP}$ or $\frac{a}{a+b}$.

Negative Predictive Value (NPV)

The probability that a patient does not have the disease given that their test result is negative, calculated as $\frac{TN}{FN + TN}$ or $\frac{d}{c+d}$.

Reliability

The extent to which an experiment, test, or measuring procedure yields the same results on repeated trials.

Intrasubject Variation

Variation in test results caused by biological changes in human characteristics within a single individual over time.

Intraobserver Variation

Variation that occurs between two or more readings of the same test results made by the same observer.

Interobserver Variation

Variation that occurs when two or more different examiners do not yield the same test result.

Kappa Statistic

A measure of test agreement calculated as $\text{Kappa} = \frac{(\%\text{ agreement}) - (\%\text{ chance agreement})}{100\% - (\%\text{ chance agreement})}$.

Gaussian Distribution

A normal, unimodal continuous probability distribution discovered by Carl Friedrich Gauss in 1809 as a way to rationalize the method of least squares.