Skewness

Calculates how symmetrical the data-set is, zero indicates perfect symmetry.

Interpretation

>0 the higher the Skewness value is the more skewness is to the left.
=0 is normal.
<0 the lower the Skewness value is the more skewness is to the right.

Data file

What can cause Skewness

1. Lifetime data is often not normal distributed (wear out)
2. Data is close to zero or a other limit
3. Mix of more distributions
4. With a small sample size the skewness value can not be trusted

How statistically deal with Skewed data

See What to do with not normally distributed data.

Formula

Legend

n = n
=Mean

External links

• http://en.wikipedia.org/wiki/Skewness
• http://www.itl.nist.gov/div898/handbook/eda/section3/eda35b.htm
• http://statistics.about.com/od/Descriptive-Statistics/a/What-Is-Skewness.htm