A manufacturing company produces part A732 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 A732 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 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?
A)2
B)3
C)50
D)520
E)570

Question

Quizplus · Accepted Answer

The degrees of freedom for a chi-square test of independence is calculated as (number of rows - 1) * (number of columns - 1). Here, there are 3 processes (rows) and 2 outcomes (defective or not defective, columns), so the degrees of freedom is (3-1)*(2-1) = 2.

A Manufacturing Company Produces Part A732 for the Aerospace Industry