Question 7.34

7.34 Executives learn Spanish.

A company contracts with a language institute to provide instruction in Spanish for its executives who will be posted overseas. The following table gives the pretest and posttest scores on the Modern Language Association’s listening test in Spanish for 20 executives.15

spnish

Subject Pretest Posttest Subject Pretest Posttest
1 30 29 11 30 32
2 28 30 12 29 28
3 31 32 13 31 34
4 26 30 14 29 32
5 20 16 15 34 32
6 30 25 16 20 27
7 34 31 17 26 28
8 15 18 18 25 29
9 28 33 19 31 32
10 20 25 20 29 32
  1. We hope to show that the training improves listening skills. State an appropriate and . Describe in words the parameters that appear in your hypotheses.
  2. Make a graphical check for outliers or strong skewness in the data that you will use in your statistical test, and report your conclusions on the validity of the test.
  3. Carry out a test. Can you reject at the 5% significance level? At the 1% significance level?
  4. Give a 90% confidence interval for the mean increase in listening score due to the intensive training.