Symmetry and Skewness

Symmetry(대칭)

Shape of distribution is thought to be symmetrical if it can be divided into two parts that looks equal.

 

Skeweness(비대칭도, 왜도)

Shape of distribution is thought to be skewed if it is asymmetrical.

Skewed to the left means that most of the values in data is clustered on the bigger side. In this case, the mean is less than the median.

Skewed to the right means that most of the values in data is clustered on the smaller side. In this case, the mean is bigger than the median.

In box plots, you can see the symmetry of box or length of whiskers to determine the skewness:

*Kurtosis(첨도)

Kurtosis means how much the values are close to the average.

Mesokurtic is the shape of the standard distribution.

In Leptokurtic distribution, the values are much closer to the average than standard deviation.

In Platykurtic distribution, the values are far from the average than standard deviation.