One common test for HIV/AIDS is the ELISA test. A study by Gastwirth (1987) esti

Question

One common test for HIV/AIDS is the ELISA test. A study by Gastwirth (1987) estimates that when a person actually carries the AIDS virus, this test produces a positive result 97.7% of the time. When a person docs not carry the AIDS virus, the test result is negative 92.6% of the time. The study further claims that a base rate of about 0.5% of the American population carries the AIDS virus. That is. the base rate is the probability a randomly selected individual carries the virus. For the people who test positive, what is the probability they actually have the disease?

Explanation / Answer

Let pos: positive D: disease A: Not positive B: no disease P(D/Pos)= P(pos/D) P(D)/P(Pos) = (0.977) ( 0.005)/ 0.0785= 0.0622 So the probability is P(pos)= P(Pos/D) P(D)+ P(Pos/B) P(B) = (.977) (0.005) + (0.074) (0.995)= 0.0785

Related Questions

Navigate

• Browse (All)
• Browse O
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.