In a study to determine the effectiveness of using a drug to treat multiple sclerosis, 488 subjects were given the drug and 244 subjects were given a placebo. The numbers of subjects who had 12-week confirmed disability progression were tracked. The results are shown at the left. At a = 0.01, can you support the claim that there is a difference in the proportion of subjects who had no 12-week confirmed disability progression?

(a) Identify the claim and state H₀ and H_a, 

(b) Find the critical value(s) and identify the rejection region(s), 

(c) Find the standardized test statistic z, 

(d) Decide whether to reject or fail to reject the null hypothesis, and 

(e) Interpret the decision in the context of the original claim. Assume the samples are random and independent.

How Many Subjects Had 12-Week Confirmed Disability Progression and How Many Did Not? Disability progression. 161 96 No disability No disability progression 327 progression 148 Drug Placebo