Suppose that a randomized comparative experiment studies the effect of diet on blood pressure. Researchers divide 5454 healthy white males at random into two groups. One group receives a calcium supplement, and the other group receives a placebo. At the beginning of the study, the researchers measure several variables on the subjects. The average seated systolic blood pressure of the 2727 members of the placebo group is reported to be x̄ = 114.9, with a standard deviation of s = 9.3.
Give a 95% confidence interval for the mean systolic blood pressure of the population from which the subjects were recruited. Report your interval values to one decimal place.
95% confidence interval:
The recipe you used to calculate the 95% confidence interval requires an important assumption about the 2727 men who provided the data. What is this assumption?
The subjects in the placebo group are a simple random sample (SRS) of the healthy white males in the experiment.
The number of men in the placebo group is a reasonably small enough sample to use the formula for a confidence interval for a population mean.
The subjects in the placebo group are a simple random sample (SRS) of healthy white males.
The number of men in the placebo group is randomly chosen from the population of healthy white males.