Basic Statistics

26 POPULATIONS AND SAMPLES

2.7

2.8

freshmen, sophmores, juniors, and seniors since it is thought that the attitudes

might change as the students get more experience with the system. The inves-

tigator would like to make estimates for each class as well as the total body of

undergraduates. Choose a method of sampling and give the reasons for your

choice.

You have examined last year’s pathology records at a hospital and have found

records of 100 women who have newly diagnosed breast cancer. You are in-

terested in studying whether or not risk factor X, which is believed to have its

effect on risk in women whose cancer is diagnosed when they are <50 years

old, has had a significant effect in the population from which these women

came. Describe how you would choose a suitable sample of controls.

Randomize 24 patients who will receive either treatment A or B into three

blocks of eight patients each so that in each block, four patients get treatment

A and four patients get treatment B.

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