Air traffic controllers are required to undergo periodic random drug testing. A urine test is used for initial screening. This test detects the presence of drugs such as amphetamines, opiates and barbiturates. Its sensitivity is 0.96 and its specificity is 0.93. Aviation authorities know from past drug testing that the probability (prevalence) of drug use by air traffic controllers at a given time is 0.007.
(ii) Calculate the probability that the test is positive.
(iii) One air traffic controller returns a positive result. What is the probability this controller had used one of the drugs.
How exactly do you calculate? :? :?:
(ii) Calculate the probability that the test is positive.
(iii) One air traffic controller returns a positive result. What is the probability this controller had used one of the drugs.
How exactly do you calculate? :? :?: