Question

A large factory that builds machines has three shifts, one that starts at 4:00 A.M., one that starts at noon, and one that starts at 8:00 P.M. The manager of the factory wanted to know whether there is an association between an employee’s work experience (less than five years with the company, between five and twenty years with the company, over twenty years with the company) and the time of the employee’s shift. The manager selected a random sample of 125 employees and classified employees by their shift time and work experience. Which of the following is an appropriate pair of hypotheses for the manager to use?

A. H0 : Work experience is independent of the time of an employee's shift.
Ha, : Work experience is dependent on the time of an employee's shift.
B. H0 : Employees with over 20 years of experience are just as likely to start work
at 8PM
Ha : Employees with over 20 years of experience are less likely to start work
at 8 P.M.
C. H0 : There is an association between work experience and an employee's shift.
Ha : There is no association between work experience and an employee's shift.
D. H0 : For each shift, there is no difference between the proportions of work
experience level
Ha : For each shift, there is a difference between the proportions of work
experience level.
E. Ha : Among those in the sample, the proportion of employees for each work
experience level did not differ by shift.
Ha : Among those in the sample, the proportion of employees for each work
experience level did differ by shift.

Answer 1

A) H0 : Work experience is independent of the time of an employee’s shift.

Ha : Work experience is dependent on the time of an employee’s shift.

Explanation:

A chi-square test of independence is appropriate. The null hypothesis expresses that there is not an association between two categorical variables (work experience and time of shift) and the alternative hypothesis expresses that the categorical variables are associated.

Answer 2

An appropriate pair of hypotheses for the manager to use is:

C.

H0 : There is an association between work experience and an employee's shift.

Ha : There is no association between work experience and an employee's shift.

Explanation:

These research hypotheses compare the incidence of employee's work experience and the baseline group (the employee's shift).

These hypotheses tests are statistical tools which assess whether or not there is an association between the two variables (work experience and shift).

The null hypothesis test will provide the probability of the type 1 error (p-value).

Based on the result, the research will accept or reject the null study hypothesis.