14. A developmental psychologist is examining problemsolving ability for grade school children. Random samples of 5-year-old, 6-year-old, and 7-year-old children are obtained with n = 3 in each sample. Each child is given a standardized problem-solving task, and the psychologist records the number of errors. The data are as follows:

5-year-olds 6-year-olds 7-year-olds 5 6 4 4 1 G = 30 6 2 2 IX2 = 138 T= 15 T= 12 T= 3 55 = 2 55 = 8 55 = 2 PROBLEMS 367

a. Use these data to test whether there are any significant differences among the three age groups. Use a = .05.

b. Use the Scheffe test to determine which groups are different.