5) Suppose a certain drug test is93% accurate, meaningthat if aperson is a user,
ID: 3064356 • Letter: 5
Question
5) Suppose a certain drug test is93% accurate, meaningthat if aperson is a user, the result is positive 93% of the time, and if she or he isn't a user, it's negative 93% of the time. Assume that 7% of all people are drug users. Fill in the following table assuming that the population is 10,000. Drug user Not a drug user Totals Test positive Test negative Totals 10,000 Suppose a randomly chosen person from the population in question tests positive. How likely is the individual to be a drug user? That is, what is the PPV of this test for this population? What does this mean about the effectiveness of the test?Explanation / Answer
P(drug user|test positive)=651/1302= 0.50
PPV =true posiitve/total positive =651/1302 =0.5
which means the probability of a true posiitive given test came out positive.
drug user not drug user total test positive 651 651 1302 test negative 49 8649 8698 total 700 9300 10000