Skew (skew distribution)

For our purposes a skew distribution is an asymmetric one: one which has a longer tail towards either higher scores or lower scores rather than two fairly equally long tails. This matters to us for two reasons.

1. Distributions of scores from different clients on our measures are rarely symmetrical, and
2. Traditional (“parametrical”) statistical methods assume symmetrical (actually generally one specific symmetrical distribution: the Gaussian or “Normal” distribution) and can be quite misleading when applied to skew distributions.

Details #

Here is a histogram of a symmetrical distribution.

Here is a histogram of a positively skew distribution.

You can see that the tail of the distribution goes off to the right, to the higher scores. Finally, here is a negatively skew distribution.

Try also #

Distribution
Histogram

Chapters #

Chapter 5

Online applications #

In due course I hope to have a shiny app to plot histograms of data.

Dates #

Created 1/11/21