Hypothesis Testing Problems

1. In the population of young workers in the retail industry in Canada, the mean workplace aggression score on the Workplace Aggression Questionnaire (WAQ) is = 6 with a standard deviation of = 4. You are a psychologist specializing in interpersonal relations and violence intervention. You provide a sample of n=15 young workers working in retail with a 3 hour training session on managing workplace aggression. You measure the experiences of workplace aggression of the young workers two weeks after the training session and get the following scores:

4, 7, 2, 8, 3, 10, 8, 2, 3, 9, 7, 5, 4, 10, 6.

a. What is the mean of the sampling distribution for this population? (Hint: This is not the sample mean)

b. What is the standard error of the sampling distribution (what is _M; hand calculation question)?

c. What is the z of the sample mean (Hypothesis Testing) of the 15 young workers after training (hand calculation question)?

2. Conduct a hypothesis test of whether the training significantly changed the experiences of workplace aggression among the young workers with a rejection region or alpha of =.05 by following these steps:

a. State your hypotheses, and define your population parameters.

• What is your Null Hypothesis?
• What is your Alternative Hypothesis?

b. Define your critical region.

• What are the value/s of z that define your rejection region?

c. Run your test.

• You already did this in 1.d. What is the value of your test statistic?

d. Compare your sample statistic to your population parameter.

• Is your sample mean z score extreme enough to reject the null hypothesis?

e. State your conclusion from this statistical hypothesis test.

f. State your research conclusion: What does your study tell us?