A manufacturing company produces part 2205 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 2205 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 .05 we performed 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?
A)2
B)3
C)520
D)569
E)570

Question

Quizplus · Accepted Answer

The degrees of freedom for the chi-square test of independence is calculated as df = (number of rows - 1) x (number of columns - 1). In this case, there are 3 processes and 2 outcomes (defective and non-defective), so df = (3-1) x (2-1) = 2. Therefore, the answer is choice letter B.

A Manufacturing Company Produces Part 2205 for the Aerospace Industry