Wednesday, July 7, 2010

Skewness-Lack of symmetry in frequency distribution


Meaning of Skewness:

The term skewness means lack of symmetry in a frequency distribution. Skewness denotes the degree of departure of a distribution from symmetry and reveals the direction of scatterness of the items. It gives us an idea about the shape of the frequency curve. When a distribution is not symmetrical , It is called a skewed distribution. Skewness tells us about the asymmetry of the frequency distribution.

Definition of Skewness:



  1. Skewness is the degree of asymmetry or departure from symmetry of a distribution --------  M. R. Speigal.
  2. When a series is not symmetrical , it is said to be asymmetrical or skewed-------------Croxten and Cowden.
  3. By skewness of a frequency distribution , we mean degree of its departure from symmetry----------Simpson and kafka.

Skewness and frequency Distribution:

  1.  Symmetrical Distribution:
    In a symmetrical distribution or symmetrical curve , skewness is not present. The values of mean , median and mode coincide i.e. Mean=Meadian=Mode. The spread of the frequencies is the same on both sides of the central point curve.
  2. Skewed Distribution:
    A distribution which is not symmetrical is called skewed distribution or asymmetrical distribution . 
    A skewed distribution may be either positively skewed or negatively skewed.
    1. Positively skewed: If the longer tail of the frequency curve of distribution lies to the right of the central point, it is called a positively skewed distribution.In Positively skewed distribution , the  value of the  mean will be greater than median and median will be greater than mode.
    2. Negatively skewed.: If the longer tail of the frequency curve of the distribution lies to the left of the central point , it is called a negatively skewed distribution. In the negatively skewed distribution , the value of the mean will be less then median be less than mode.
    Formula for calculating Skewness is given in below fig.

    1 comment:

    ProPlus Academy said...

    Thanks for Sharing Information to us. If Someone wants to know about Digital Marketing and SEO Courses this is the Right place for you!
    digital marketing course in coimbatore and
    SEO courses in coimbatore