Calculate Mean Variance and Skewness

In this video we calculate the Mean (arithmetic), Standard Deviation, Variance, Skewness.
First, we calculate the Mean which is then helpful to calculate the Variance.
The Standard Deviation is the square root of the Variance.
The Skewness is the sum of all the differences between the data points and the mean, of which each difference is cubed. We divide this by 1 less than the number of observations multiplied by the standard deviation cubed. This will give us a value which is either negative, zero or positive.
If the skewness is zero, then the data is symmetrical, and the mean median and mode will be equal.
If the skewness is negative, then the data will have left tail, where the mean is to the left of the data.
If the skewness is positive, then the data will have right tail, where the mean is to the right of the data.
There is also an example where the skew is undefined.
Then we attempt to draw the graph of the data.

#skewness
#statistics
#descriptive
#stats_videos
#maths
#variance
#deviation
#arithmetic_mean
#mean
#statistics4all

There is an excellent article on skewness here

[richardweston]

If it had been Redcar last week, I think I would have walked out

[marcashford]

use the same notations, you used sample mean and population variance