There are two manufacturing processes, old and new, that produce the same product. The defect rate has been measured for a number of days for each process, resulting in the following summaries (Table 10.7.10).
a. By how much would we estimate that the defect rate would improve if we switched from the old to the new process?
b. What is the standard error of your answer to part a?
c. Your firm is interested in switching to the new process only if it can be demonstrated convincingly that the new process improves quality. State the null and research hypotheses for this situation.
d. Find the appropriate one-sided 95% confidence interval for the (population) long-term reduction in the defect rate.
e. Is the improvement (as estimated in part a) statistically significant?

TABLE 10.7.10 Defect Rate Summaries for Two Manufacturing Processes Old New 0.047 Average defect rate Standard deviation Sample size (days) 0.023 0.068 0.050 50