Sensitivity and Specificity Testing Flashcards
What is known as the true-positive rate?
Sensitivity
What is known as the proportion of people with the disease who test positive?
True-positive AKA sensitivity
Equation of Sensitivity
TPV/TD
What is known as the true-negative rate?
Specificity
What is known as the proportion of people testing negative who do not have the disease?
True-negative AKA specificity
Equation of specificity
TNV/TND
What is a downside of a highly sensitive test?
A higher rate of false positives
What is an example of a high sensitivity and low specificity test?
Mammogram - depends on tumor size and patient age
What is the downside of a test with high specificity?
A high false negative rate
What is an example of a test with high specificity?
Nitrate dipstick used for UTI’s
What is the positive predictive value (PPV)?
Probability of patients testing positive who actually have the disease
Equation for PPV
TPV/TP
What are PPV influenced by?
How common the disease is
What is the negative predictive value (NPV)?
Probability of patients testing negative who truly don’t have the disease
Equation for NPV
TNV/TN