by Dawn Wright | Jul 23, 2018

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...
by Dawn Wright | Apr 25, 2018

Enter your data in the blue cells and the answers will be in the yellow cells.
by Dawn Wright | Mar 31, 2018

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 workbookÂ Min Sample Size for Mean CI...
by Dawn Wright | Mar 29, 2018

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...
by Dawn Wright | Mar 29, 2018

If you are conducting a survey, you will need to decide on the number of people you need to sample. That, of course, depends upon how confident you want to be and how accurately you want to predict the population proportion based on your survey results. If you want to...