Table : TABLE 12-10. A Completed Source Table Once we calculate the sums of squares and the degrees of freedom, the rest is just simple division. We use the first two columns of numbers to calculate the variances and the F statistic. We divide the between-groups sum of squares and within-groups sum of squares by their associated degrees of freedom to get the between-groups variance and within-groups variance. Then we divide the between-groups variance by the within-groups variance to get the F statistic, 8.27.