One criterion used to evaluate employees in the assembly section of a large factory is the number of defective pieces per 1,000 parts produced. The quality control department wants to find out whether there is a relationship between years of experience and defect rate. Since the job is repetitious, after the initial training period any improvement due to a learning effect might be offset by a loss of motivation. A defect rate is calculated for each worker in a yearly evaluation. The results for 100 workers are given in the table below.
Years Since Training Period
< 1 Year 1-4 years 5-9 Years
Defect Rate High 6 9 9
Average 9 19 23
Low 7 8 10
Referring to the table above, which test would be used to properly analyze the data in this experiment to determine whether there is a relationship between defect rate and years of experience?
A. ANOVA F test for main treatment effect
B. Z test for difference in two proportions
C. X2 test for equal proportions is higher than another
D. X2 test for independence in a two-way contingency table
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Chi square test of Independence.