# Chi square test of Independence

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

See attached file for full problem description.

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#### Solution Summary

Chi square test of Independence.