In exercises that call for two-sample procedures, you may use either of the two approximations for the degrees of freedom that we have discussed: the value given by your software or the smaller of and . Be sure to state clearly which approximation you have used.

Question 7.48

7.48 Determining significance.

For each of the following, answer the question and give a short explanation of your reasoning.

  1. A significance test for comparing two means gave with 11 degrees of freedom. Can you reject the null hypothesis that the ’s are equal versus the two-sided alternative at the 5% significance level?
  2. Answer part (a) for the one-sided alternative that the difference in means is negative.
  3. Answer part (a) for the one-sided alternative that the difference in means is positive.