L. Petersen et al. evaluated the effects of integrated treatment for patients with a first episode of psychotic illness in the paper "A Randomised Multicentre Trial of Integrated Versus Standard Treatment for Patients With a First Episode of Psychotic Illness" (British Medical Journal, Vol. 331, (7517):602). Part of the study included a questionnaire that was designed to measure client satisfaction for both the integrated treatment and a standard treatment. The data on the WeissStats CD are based on the results of the client questionnaire.
Use the technology of your choice to do the following.
a. Obtain normal probability plots, boxplots, and the standard deviations for the two samples.
b. Based on your results from part (a), which would you be inclined to use to compare the population means: a pooled or a nonpooled t-procedure? Explain your answer.
c. Do the data provide sufficient evidence to conclude that, on average, clients preferred the integrated treatment? Perform the required hypothesis test at the 1% significance level by using both the pooled t-test and the nonpooled t-test. Compare your results.
d. Find a 98% confidence interval for the difference between mean client satisfaction scores for the two treatments.
Obtain the required confidence interval by using both the pooled t-interval procedure and the nonpooled t-interval procedure.