Bias 10: Regression to the Average

Your company has 3 shops of the same size with the same products. The predictions are that the total sales of your company will increase by 10% in 2013. Complete the following tab:

2012 2013
Shop 1 10 000 ?
Shop 2 20 000 ?
Shop 3 100 000 ?
TOTAL 130 000 143 000

Most people tend to increase the sales of each shop by 10% while it is more plausible that extreme values (Shop 3 and 1) will regress to the average. This bias is called the regression to the average effect.

Reference:

Thinking fast and slow, D.Kahneman