Chapter 18
1. Why can't the probability value be used as a measure of effect size?
2. The following data are from an experiment in which comparing three kinds
of cat food. Cats were randomly assigned to one of three groups.
Group 1 was fed "Good and Fishy,"
Group 2 was fed “Cat’s Delight," and
Group 3 was fed "Lovely Livers." The time (in seconds) taken to eat
a sixonce can of food was recorded. Compute
and .
Good and Fishy

Cat's Delight

Lovely Livers

12
15 11 10 
18 
32 
3. If the correlation between X and Y is 0.30, what is the proportion of the
Y variance is explained by X?
4. The effectiveness of a drug is evaluated by comparing the proportion of patients
showing improvement with the drug to the proportion showing improvement with
a placebo. Of 50 patients taking the drug, 15 showed improvement; of 50 taking
the placebo, 6 showed improvement. Compute f.
5. How can the choice of levels of an independent variable affect ?