Simulation
This page performs a simulation to illustrate the theoretical distribution of the difference between two sample means.
Irrespective of the distributions within the two
groups,
Click Accumulate then take several samples.
An experiment was conducted on volunteers who developed a cold within the previous 24 hours. They were randomised to take either zinc acetate lozenges or placebo lozenges (identical but with no active ingredient). The duration of cold symptoms for the subjects who received zinc had mean 4.5 days, and standard deviation 1.6 days. The control group's duration had mean 8.1 days, and standard deviation 1.8 days.
The simulation uses these means and standard deviations as population parameters.