A researcher wants to determine if a new schizophrenia drug has different effects on patients compared to a placebo. A total of n₁ = 20 people took the new drug for six weeks and n₂ = 20 people took a placebo for 6 weeks. She then assesses their symptoms. The group of participants who took the new drug showed an average of xbar₁ = 7.4 major symptoms a day after the six weeks, with a standard deviation of S₁ = 2.6. The group of participants who took the placebo displayed on average of xbar₂ = 7.6 major symptoms a day after the six weeks, with a standard deviation of S₂ = 2.2

A) Please calculate and report the appropriate statistic, showing all your steps.

B) Based on an alpha = .05, critical values of +/- 2.06, and obtained (calculated) the test statistic from part A, should you retain or reject the null hypothesis?

C) Would the p-value be bigger or smaller than alpha?

D) Please construct and interpret the follow-up confidence interval that would be the most appropriate for these data. Hint: does the interval contain the null value for this type of test?

E) In everyday language, what do these results tell you about the research question? Does which drug someone takes (real versus placebo) impact their symptoms?

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