Confidence Intervals

A Study in Determining Confidence Intervals at 95%

Charlesatta Johnson

PH6014

October 9, 2013

Dr. Rodrick Frazier

A Study in Determining Confidence Intervals at 95%

As hypothesized, high cholesterol levels in children can lead to their children being affected with hyperlipidemia. A study is conducted to estimate the mean cholesterol in children between the ages of 2 - 6 years of age. It also attempted to establish a correlation as to the effect family history has on the onset of the disease. From data collected as shown in Table 1 of the spreadsheet attached, a sample size of 9 (n=9) participants enrolled in the study. Total cholesterol levels measured in children between ages 2 – 6 years was summarized at 1,765. The sample mean (X) and standard deviation (S) computed as (1765/90) =196.1 and square root summation (X-X) square / n-1 =29.0 respectively. Now to generate a 95% confidence interval for the true mean total cholesterol levels in children from data collected, we used the z value for 95% as (z= 1.96). From sample statistics the confidence interval for 95% computed from the formula is (196.1 +/- 1.96 X 29/3) we now have 196.1 +/-19.0. Now, by adding and subtracting the margin of error, we have (215.1, 177.1) respectively. A point estimate for the true mean cholesterol levels in the population is 196.1 and that we are 95% confident that the true mean is between 215.1 and 177.1. The margin or is large because of the small sample size.

A pilot study with 10 participants was conducted to assess how systolic blood pressure changes overtime if left. Clinical trial compared experimental medication designed to lower to that of a placebo. The sample mean (X) for the difference in blood pressures over a four weeks period is computed as (9/10) =0.09 or 90%. Also, the standard deviation for the difference over the same four weeks period computed as [(X) 2/square root n-1] = 183/20.33= 4.5, and. Z value =1.96. The confident interval (CI) for 95%...