Question

​A sample of 126 corporate managers and another sample of 168 college professors produced mean job-related stress scores of 7.35 for the managers and 6.86 for the professors. Suppose that the standard deviations of the stress scores are 1.12 for the managers and 1.82 for the professors. The null hypothesis is that the mean stress scores are the same for corporate managers and college professors, while the alternative hypothesis is that the mean stress score for managers is different from the mean stress score for professors. The significance level for the test is 1%. What are the critical values of z?

Answer 1

To solve this problem, all we have to do is to search for or locate the corresponding z crit value given the confidence level of the test. There is no need to calculate since tables are already provided in text books or the internet.

Now, we can consider this problem as a two way z test since we can set the upper and lower control limit. Given that information and a significance level of 1%, therefore this means that the area on the upper side and the area on the lower side has a total of 2% of the total stress scores (1% each). Therefore the confidence level is 98%. From the tables, this corresponds to a critical z values of:

- 2.33 and 2.33                   (ANSWER)