Question

In the Framingham Offspring study 1573 subjects were on anti-hypertensive medication out of 3645 total subjects. What is the length of the 99 percent confidence interval for this data.

Note: Round your answer to 4 decimal places.

Answer 1

$p=\frac{1573}{3645}=0.4316.$

$99\%CI=(p-z_{0.005}\sqrt{\frac{p(1-p)}{n}}, p+z_{0.005}\sqrt{\frac{p(1-p)}{n}})=$

$=(0.4316-2.3263\sqrt{\frac{0.4316(1-0.4316)}{3645}},0.4316+2.3263\sqrt{\frac{0.4316(1-0.4316)}{3645}})=$

$=(0.4125, 0.4507).$

The lenght of the confidence interval: $W=0.4507-0.4125=0.0382.$