## Confidence Interval for a Proportion

Excel solution StatCruch solution

Joe, I think you are understanding confidence intervals, but I am not sure I am understanding your comments. So, let me restate them a bit. A 95% confidence interval means that if you repeat exactly the same process/experiment many times, 95% of the time the population parameter, e.g. the mean, will fall within that interval. …

A bigger hoop is better: why confidence intervals get wider as the confidence increases Read More »

Enter your data in the blue cells and the answers will be in the yellow cells.

Enter your data in the blue cells and the minimum sample size will be in the yellow cell at the bottom. Note: the standard deviation and E must be in the same units (e.g. inches, feet, etc). Download a copy of the workbook Min Sample Size for Mean CI V1.00

If you are given summary data and asked to find a confidence interval, it is relatively easy using StatCrunch. Here is a typical problem: In this problem, you are told to use the t-distribution, but that may not always be the case. If you are given the sample standard deviation, s, instead of the population …