Skewness

Skewness is an asymmetrical frequency distribution in which the values are concentrated on one side of the central tendency and trail out on the other side. If the trail is to the right or positive end of the scale, the distribution is said to be positively skewed. If the distribution trails off to the left or negative side of the scale, it is said to be negatively skewed.

Positive Skew


Negative Skew


Sources:

http://www.brendan.com/glossary.html

http://cnx.org/content/m11011/latest/