Skewness of Random Variable

1. Skewness of Random
Variable
MR. ANTHONY F. BALATAR JR.
SUBJECT INSTRUCTOR

2. Basic Concepts on Skewness
Skewness – the measure of symmetry or asymmetry
of the probability distribution of a random variable
about the mean.
To find the skewness, subtract the median from the
mean, multiply the difference by 3, and divide the
product by the standard deviation.
In symbols,
[3(mean–median)]/standard deviation

3. Basic Concepts on Skewness
If skewness is -1> x > 1, the distribution is highly
skewed.
If skewness is between -1 and -0.5 or between 0.5
and 1, then the distribution is moderately skewed.
If skewness is between -0.5 and 0.5, then the
distribution is approximately normal or symmetrical.

4. Basic Concepts on Skewness
 If the mean is equal to the median, the distribution is
symmetrical.
 If the mean is less than the median, the distribution is
concentrated on the right side and the left tail is longer.
This is a negatively skewed distribution.
 If the mean is greater than the median, the distribution is
concentrated on the left side and the right tail is longer.
This is a positively skewed distribution.