Skewness and Kurtosis

Skewness

The coefficient of Skewness is a measure for the degree of symmetry in the variable distribution (Sheskin, 2011).

Negatively skewed distribution or Skewed to the left Skewness <0		Normal distribution Symmetrical Skewness = 0		Positively skewed distribution or Skewed to the right Skewness > 0

Kurtosis

The coefficient of Kurtosis is a measure for the degree of tailedness in the variable distribution (Westfall, 2014).

Platykurtic distribution Thinner tails Kurtosis <0		Normal distribution Mesokurtic distribution Kurtosis = 0		Leptokurtic distribution Fatter tails Kurtosis > 0

Literature

• Sheskin DJ (2011) Handbook of parametric and non-parametric statistical procedures. 5^th ed. Boca Raton: Chapman & Hall /CRC.
• Westfall PH (2014) Kurtosis as Peakedness, 1905 - 2014. R.I.P. The American Statistician 68:191-195.

See also

• Summary statistics
• Reference interval
• Tests for Normal distribution

External links

• Skewness on Wikipedia.
• Kurtosis on Wikipedia.