Question

Technician           Technician

1                              2

1.45                        1.54

1.37                       1.41

1.21                        1.56

1.54                        1.37

1.48                        1.2

1.29                        1.31

1.34                        1.27

1.35

Two quality control technicians measured the surface finish of a metal part, obtaining the data in the table below. Assume that the measurements are normally distributed.

a. Test the hypothesis that the mean surface finish measurements made by the two technicians are equal. Use α = 0.05 and assume equal variances. b. What are the practical implications of the test in part (a)? Discuss what practical conclusions you would draw if the null hypothesis were rejected. c. Assuming that the variances are equal, construct a 95% confidence interval on the mean difference in surface-finish measurements d. Test the hypothesis that the variances of the measurements made by the two technicians are equal. Use α = 0.05. What are the practical implications if the null hypothesis is rejected? e. Construct a 95% confidence interval estimate of the ratio of the variances of technician measurement error.

Answer 1