Results of a survey by the National Center for Health Statistics indicated that people between 65 and 74 years of age contact a physician an average of 9.8 times per year. People 75 and older contact doctors an average of 12.9 times per year. Suppose you want to validate these results by taking your own samples. The following data represent the number of annual contacts people make with a physician. The samples are independent. Use a Mann-Whitney U test to determine whether the number of contacts with physicians by people 75 and older is greater than the number by people 65 to 74 years old. Let α = .01.
65 to 74 .... 75 and Older
12 ...... 16
13 ...... 15
8 ...... 10
11 ...... 17
9 ...... 13
6 ...... 12
11 ...... 14
9
13