Question

A study is conducted concerning the blood pressure of 60-year old women with glaucoma. In the study a random sample of 1000 60-year old women with glaucoma was taken and the sample mean systolic blood pressure was 132 mm Hg and the sample standard deviation was 23 mm Hg.

A)The sample standard deviation of 23 mm Hg is an estimate of what (i.e: this is an estimate of the variation in what values?)

B) Based on the sample results, what is the estimated standard error of the sample mean?

C) Using the sample results given, estimate a 95% confidence interval for the true mean blood pressure of all 60-year old women with glaucoma.

D) Using the sample results given, estimate a 90% confidence interval for the true mean blood pressure of all 60-year old women with glaucoma.

E)Was your interval in (d) wider or narrower than the interval in (c)?Explain why the interval is wider or narrower.

F) Suppose instead of 1000 women, the study had a random sample of 250 women 60-years old with glaucoma instead. Assuming the sample mean and standard deviation estimates were the same, what is the estimated 95% confidence interval based on this sample of only 250 such women?

G)Was your interval in (f) wider or narrower than the interval in (c)? Explain why the interval is wider or narrower.

Answer 1