This is documentation for Mathematica 8, which was
based on an earlier version of the Wolfram Language.

MeanDifferenceCI

 gives a confidence interval for the difference between the population means estimated from and .
• gives a confidence interval centered at Mean[list1]-Mean[list2].
• is based on a normal distribution if the population variances are assumed known.
• If the variances for the two populations are assumed equal and unknown, the interval is based on Student's t distribution with Length[list1]+Length[list2]-2 degrees of freedom.
• If the population variances are not assumed known and not assumed equal, Welch's approximation for the degrees of freedom is used.
• The following options can be given:
 ConfidenceLevel 0.95 probability associated with a confidence interval EqualVariances False whether the unknown population variances are assumed equal KnownVariance None list of variances of each population
The 95% confidence interval for the difference in two population means:
Needs["HypothesisTesting`"]
The 95% confidence interval for the difference in two population means:
 Out[2]=
 Options   (3)
The 99% confidence interval:
A confidence interval assuming equal but unknown variances:
A confidence interval assuming known variances: