Effect of zinc lozenges on cold duration

Use this page to explain that we are interested in the difference between the groups and, in particular, the difference between the group means, . However this difference is random, so we must understand its distribution before we can interpret its value.

The simulation is based on a real data set, but only mention that the difference between the model's group means is µ2  - µ1 = 3.6 days. Take several samples and mention the variability in the difference between the sample means. (The light blue bands for each group are µ ± 2σ.)

Now select Actual data set from the pop-up menu.

To interpret what the difference between the sample means tells you about µ2  - µ1, you must understand its distribution.

Zinc and colds

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 deviation1.6 days. The control group's duration had mean 8.1 days, and standard deviation 1.8 days.

The simulation uses these values as population parameters.

Birth weights in summer and winter

This example is described in the diagram