Critical Analysis

Question 1

Sensitivity
Define and formula

Answer 1

Proportion of patients with the disease who have positive test result

TP/(TP + FN)

Question 2

Specificity - define and formula

Answer 2

Proportion of patients without the disease who have negative test result

TN/(TN + FP)

Question 3

Positive predictive value - define and formula

Answer 3

The chance the patient has the condition if the test is positive

TP/(TP + FP)

Question 4

Negative predictive value - define and formula

Answer 4

Chance patient does not have condition of test is negative

TN/ (TN + FN)

Question 5

Likelihood ratio for positive test result - define and formula

Answer 5

How much the odds of a disease increase when result is positive

Sensitivity/(1- specificity)

Question 6

Likelihood ratio for a negative test result - define and formula

Answer 6

How much the odds of a disease decrease when the test is negative

(1 - sensitivity) / specificity

Question 7

Number needed to treat formula

Answer 7

1/absolute risk reduction