Module 03 Summary

What this module established

On skewed measures the mean and standard deviation describe a distribution that does not exist: one value in sixty-one moved the mean by fourteen and the standard deviation by a factor of five, while the median moved by less than one.

Carry forward

• Carry n and the standard error through every grouped summary. A group of six was seven times as uncertain as a group of forty and still topped the ranking.
• Plot the distributions before testing the means. Two groups with means of 49.6 and 50.9 were not the same shape — one was bimodal.
• Overlapping error bars do not mean no difference. Read the interval around the difference; here two overlapping intervals came with p=0.01.
• Report the estimate, the interval, the p-value and n. 'Significant' replaces four pieces of information with none of them.

Before moving on

Move on when every sentence you have written names its measure, size, comparison and period.

Mark complete