To compare average maternal ages between smoking and non-smoking groups of mothers during the course of pregnancies, twenty-six mothers will be chosen from each of the two groups.
(a) Set up the statistical hypotheses.
(b) What is the proper test statistic to be used? (Write its formula with necessary information.)
What are the important assumptions you need to make?
(c) Sketch the distribution of the test statistic with the rejection region(s) identified when Type I error is set at 0.05.
(d) Specify your decision rule in testing the above hypotheses.
(e) Will you reject the null hypothesis if the test statistic has a value of -1.80?
(f) If in fact there is no difference between the two means, what type of statistical error you may have committed?