Question

The hospital administrator mentioned that a randomly selected 64 patients and measured the time (in minutes) between when they checked in to the ER and the time they were first seen by a doctor. The average time is 137.5 minutes and the standard deviation is 39 minutes. She is getting grief from her supervisor on the basis that the wait times in the ER has increased greatly from last year’s average of 127 minutes. However, she claims that the increase is probably just due to chance.

Using a significance level of α = 0 .05, is the change in wait times statistically significant? Use a two-sided test since it seems the supervisor had to inspect the data before she suggested an increase occurred.

Step 2: Find the critical value Z:

Answer 1

For alpha =0.05, the critical values are -1.96 and 1.96.