Ideally, results of a statistical analysis should not depend greatly on a single observation. To check this, it’s a good idea to conduct a sensitivity study: Redo the analysis after deleting an outlier from the data set or changing its value to a more typical value, and check whether results change much. For the anorexia data of Example 6.4

(available in the Anorexia CB data file at the text website), the weight change of 20.9 pounds was a severe outlier.

Suppose this observation was actually 2.9 pounds but was incorrectly recorded. Redo the one-sided test of Example 6.4 (page 148), and summarize the influence of that observation.