Question

Graeven and Jones (1976) studied a heroin epidemic in the San Francisco Bay area. A sample of 120 drug users was interview and each subject was asked to name the kind of drug that each was first injected. These data are listed below. Because previous data was inadequate, it was hypothesized that the proportions of subjects reporting “type of first drug injected” would be 60% for heroin, 30% for speed, and 10% for all others. Test the hypothesis that the probabilities for type of drug first injected do not differ from the hypothesized proportion given above.

First drug injected | number

Heroin 60

Speed 40

other 20

Total 120

(a) State the null hypothesis and alternative hypothesis

(b) Find the test statistic

(c) If the type-I error α = 0.1, find the critical value(s) and shade the rejection region(s)

(d) Base on the type-I error α and rejection region(s), given above, what is your conclusion?

Answer 1