Question

A study was conducted to investigate whether a new diet lowers cholesterol. The researchers took a random sample of 100 subjects with high cholesterol and measured the cholesterol levels for each. Then each subject began the new diet as instructed. After six months, the subjects' cholesterol levels were measured again. The differences in cholesterol level, calculated as After - Before, follow an approximately normal distribution. Suppose a 99% confidence interval for the mean cholesterol difference is (-13.89, -7.66). Which of the following is a correct interpretation of this interval?

	a.	The new diet lowers each subject's cholesterol level by 7.66 to 13.89 points.
	b.	We are 99% confident that cholesterol is 7.66 to 13.89 points higher, on average, before implementing the new diet.
	c.	There is a 99% chance that cholesterol is 7.66 to 13.89 points lower, on average, before implementing the new diet.
	d.	There is a 95% chance that cholesterol is 7.66 to 13.89 points higher, on average, before implementing the new diet.
	e.	We are 99% confident that cholesterol is 7.66 to 13.89 points lower, on average, before implementing the new diet.

Answer 1

we have given the 99% confidence interval for the mean cholesterol difference is (-13.89, -7.66).

the true interpretation of confidence interval is goven by option b

.	We are 99% confident that cholesterol is 7.66 to 13.89 points higher, on average, before implementing the new diet

so option b is true