## Confidence Interval for a Proportion

Excel solution StatCruch solution

## Find Margin of Error for t-distribution Confidence Interval

## A bigger hoop is better: why confidence intervals get wider as the confidence increases

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. […]

## Confidence Interval for Difference Between Proportions

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

## Minimum Sample Size for Population Mean given c, sigma, E

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

## Confidence Interval for a Mean using StatCrunch

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 […]