Standard Deviation. But standard deviation equals the square root of variance so sd the square root of 3 85 which is 1 96. As standard deviation is one of the hardest things so it can not be calculated by hands there is still no statistician who can calculate it on hands.
So now you ask what is the variance. Standard deviation is the square root of variance but variance is given by mean so divide by number of samples. In statistics standard deviation sd is a measure of how spread out numbers are in a given set showing points of variation.
The standard deviation is a measure of how spread out numbers are.
The only reason behind it is that standard deviation is quite a complex task and there is a high risk to create a mistake and apart from this making calculation by hand is a very slow procedure. The lower the standard deviation the closer the data points tend to be to the mean or expected value μ. Standard deviation may be abbreviated sd and is most commonly. As standard deviation is one of the hardest things so it can not be calculated by hands there is still no statistician who can calculate it on hands.
