What is the Critical z value and Computed statistic? Apply the two sample z test at a 5% level of significance.

A randomized controlled trial is run to evaluate the effectiveness of a new drug for 

asthma in children. A total of 250 children are randomized to either the new drug or 

placebo (125 per group). The mean age of children assigned to the new drug is 12.4 

with a standard deviation of 3.6 years. The mean age of children assigned to the 

placebo is 13.0 with a standard deviation of 4.0 years. Is there a statistically significant 

difference in ages of children assigned to the treatments? Apply the two sample z test 

at a 5% level of significance.

1. Critical z value = +/- (2 points) 

2. Computed statistic= (2 points) 

3. Based on comparing the computed statistic to the critical value which of the following 

is (are) true? (6 points) 

a. There is significant evidence, alpha=0.05, that there is a difference in ages of children 

assigned to the treatments. 

b. There is not significant evidence, alpha=0.05, that there is a difference in ages of 

children assigned to the treatments. 

c. Statistically speaking the difference in initial weights and weights after 6 weeks is 0. 

d. b and c.