Researchers have done studies to test the effectiveness in using soy milk to tre

Question

Researchers have done studies to test the effectiveness in using soy milk to treat menopausal symptoms. These studies have had mixed results. The following, however, is not from one of these studies and is completely made up. Suppose 2 studies were done to examine the effectiveness of soy milk in treating hot flashes. The explanatory variable is whether or not a woman drinks 8 oz of soy milk or 8 oz of regular milk flavored to taste like soy milk. The response variable is # of hot flashes per day. For both studies, 200 of women were randomly assigned to either drink 8 oz of soy milk for 1 month or to drink 8 oz of regular milk flavored to taste like soy for one month (control). This was a double-blind study and the subjects were given a month's supply of the appropriate beverage. In the first study, all the women were between the ages of 55 and 58, exercise regularly, had no health problems and were not under or over weight. In the second study, the ages of the women range from 50 to 63, their exercise habits, health status and weights varied greatly. For each woman in both studies, the number of hot flashes experienced on July 1 was measured. Data from both studies was used to calculate the p-values to determine if the average number of hot flashes in the soy drinking group is statistically significantly different from the average number of hot flashes. The p-value for the first study is 0.06 and the p-value for the second study is 0.45. What could account for the difference in p-values? Because the subjects in the second study are more varied, the difference between soy group's sample average # hot flashes and the control group's sample average # hot flashes will be greater in the first study compared to the second study. Consequently, the p-value will be smaller in the first study. Because a sample size of 200 is so small, we expect a great deal of sampling variability. This results in differing p-values, even though in the population there is no association between these variables. Because the subjects in the first study are more homogeneous (more similar to each other), we expect less variation in the subjects response values in the first study (smaller sample SD in first study) resulting in a smaller the p-value for the first study. Exactly two of the above are correct.

Explanation / Answer

The correct answer is C.

third is the correct answers because the first study has a more homegenous group,hence a smaller standard deviation and a smaller p-value.

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