In industrial settings, alternative methods often exist for measuring variables of interest. The data in the file Measurement (coded to maintain confidentiality) represent measurements in-line that were collected from an analyzer during the production process and from an analytical lab (extracted from M. Leitnaker, "ComparingMeasurement Processes: In-line Versus AnalyticalMeasurements," Quality Engineering, 13, 2000 2001, pp.293-298).
a. At the 0.05 level of significance, is there evidence of adifference in the mean measurements in-line and from ananalytical lab?
b. What assumption is necessary about the population distribution in order to perform this test?
c. Use a graphical method to evaluate the validity of theassumption in (a).
d. Construct and interpret a 95% confidence interval estimate of the difference in the mean measurements in-lineand from an analytical lab.