See the attached spreadsheet with data on the "number of children" of a sample. Compute the 95% and 99% confidence intervals using Excel's descriptive statistics function: Run Data Analysis, Descriptive stats, highlight the data, check "summary statistics" as normal. Click on "Confidence Level for Man" and type in the level desired. 95% is the default.
The descriptive stats output now will include a "confidence level" number at the bottom. This is the +/- number (sometimes called the "margin of error") of the confidence interval on the mean formula.
Compare the output to that from using the "confidence interval calculator" I posted.
What does the confidence interval mean?
I have attached the solution.
This solution shows calculations in an Excel file to determine the 99% and 95% confidence level and compare the values with the values in the 'confidence interval calculator'.