## R Square

The residual sum of square, and the total sum of squares are introduced. They are used to calculate and the error variance .

The data set consists of

- explanatory variable for 's;
- dependent variable for 's.

The coefficient of determination

takes a value between 0 and 1, and represents the proportion which can be explained by the linear regression. The value indicates how close the data points are to the regression line as gets larger, and it is simply the square of the sample correlation coefficient .

can be obtained as the point estimate of the variance of error terms.