# 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.