Question by Tim C: What are the degrees of freedom for the chi-square statistic?
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: The 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 appear to be independent of the production process. What are the degrees of freedom for the chi-square statistic?
Answer by Ermite
I’m guessing it is:
df = (M-1)(N-1) = (2-1)(3-1) = 2
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