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