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 7.46

7.46 What’s wrong?

In each of the following situations, explain what is wrong and why.

  1. A researcher wants to test versus the two-sided alternative .
  2. A study recorded the credit card IQ scores of 100 college freshmen. The scores of the 48 males in the study were compared with the scores of all 100 freshmen using the two-sample methods of this section.
  3. A two-sample statistic gave a -value of 0.97. From this, we can reject the null hypothesis with 95% confidence.
  4. A researcher is interested in testing the one-sided alternative . The significance test for gave . With a -value for the two-sided alternative of 0.024, he concluded that his -value was 0.012.