A manufacturing company produces part QV2Y for the aerospace industry. This particular part can be manufactured using 3 different production processes. The management wants to know if the quality of the units of part QV2Y is the same for all three processes. The production supervisor obtained the following data: Process 1 had 29 defective units in 240 items, Process 2 produced 12 defective units in 180 items, and Process 3 manufactured 9 defective units in 150 items. At a significance level of 0.05, we performed a chi-square test of independence to determine if the quality of the items produced appears to be independent of the production process. What are the degrees of freedom for the chi-square statistic?

Question

Quizplus · Accepted Answer

Degrees of freedom = (r − 1)(c − 1) = 2 × 1 = 2, where r = no. of processes; and c = no. of categories, i.e., "defective" and "nondefective."

A Manufacturing Company Produces Part QV2Y for the Aerospace Industry