SCENARIO 12-10
One Criterion Used to Evaluate Employees in the Assembly

SCENARIO 12-10
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. $$\begin{array} { r r | c c c } & &{ \text { \quad\quad\quad Years Since Training Period } } \\& & < 1 \text { Year } & 1 - 4 \text { Years } & 5 - 9 \text { Years } \\\hline \hline{ \text { Defect Rate: } } & \text { High } & 6 & 9 & 9 \\& \text { Average } & 9 & 19 & 23 \\& \text { Low } & 7 & 8 & 10\end{array}$$
-Referring to Scenario 12-10, find the rejection region necessary for testing at the 0.05 level of significance whether there is a relationship between defect rate and years of experience. a) Reject $H _ { 0 }$ if $\chi ^ { 2 } > 16.919$
b) Reject $H _ { 0 }$ if $\chi ^ { 2 } > 15.507$
c) Reject $H _ { 0 }$ if $\chi ^ { 2 } > 11.143$
d) Reject $H _ { 0 }$ if $\chi ^ { 2 } > 9.488$