R Studio Statistics I

Sample Mean and Sample variance:

R unbiased variance :

Case:

I created one serie with the following code:

x= seq(1,20,2)

and the mean of this serie is as follow:

mean(x)

10

There are two ways to calculate sample variance:

mean((x-mean(x))^2)

or

mean(x^2)-(mean(x))^2

result is "33".

R unbiased variance is

var(x)

36.6

 and standart deviation is

sd(x)

6.05

Source:R Programming and Its Applications in Financial Mathematics