Question

Suppose two doctors, A and B, test all patients coming into a clinic for syphilis. Let events A+ = Doctor A makes a positive diagnosis and B+ = Doctor B makes a positive diagnosis. Suppose doctor A diagnoses 10% of all patients as positive, doctor B diagnoses 17% of all patients as positive, and both doctors diagnose 8% of all patients as positive.

What is the relative risk? Interpret your results in 1 – 2 sentences.

Answer 1

From the information

		Doctor A	Total
		Diagnoses is Positive	Diagnoses is Negative
Doctor B	Diagnoses is Positive	8 (a)	9(b)	17
Diagnoses is Negitive	2(c)	81(d)	83
Total		10	90	100

Relative risk is calculated by formula

Relative risk = 19.5294

Interpretation: Since value of relative risk is 19.5294 which is greater than 1 the risk of negative dignoses increased.

A negative dignoses makes by Doctor A is 19.53 times likely as negative dignoses by Doctor B.