An Arthritis Drug A study to determine theeffectiveness of a drug (serum) for arthritis

Chapter 14, Problem 45

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An Arthritis Drug A study to determine theeffectiveness of a drug (serum) for arthritis resulted inthe comparison of two groups, each consisting of 200arthritic patients. One group was inoculated with theserum; the other received a placebo (an inoculationthat appears to contain serum but actually is nonactive).After a period of time, each person in the studywas asked to state whether his or her arthritic conditionhad improved. These are the results:Treated UntreatedImproved 117 74Not Improved 83 126You want to know whether these data present sufficientevidence to indicate that the serum was effectivein improving the condition of arthritic patients.a. Use the chi-square test of homogeneity to comparethe proportions improved in the populations oftreated and untreated subjects. Test at the 5% levelof significance.b. Test the equality of the two binomial proportions usingthe two-sample z-test of Section 9.6. Verify thatthe squared value of the test statistic z2 X2 frompart a. Are your conclusions the same as in part a?