Suppose that the fit to the simple linear regression of Y on X from 6 observations produces the following residuals: -3.3, 2.1, -4.0, -1.5, 5.1, 1.6.

Question

a) What is the estimate of sigma squared?
b) What is the estimate of sigma?
c) What are the degrees of freedom?

Sigma = standard deviation
Sigma^2 = variance
(Standard deviation is the square root of the variance.)

Square the residuals, total the squared values, then divide by n-1 (n = sample size). This will be the variance. Then take the square root of the variance for the standard deviation.

I hope this will help.