[ S_xx = \sum_i=1^n (x_i - \barx)^2 = (n-1) s_x^2 ]
[ \mathrmVar\left( \fracS_xx\sigma_x^2 \right) = 2(n-1) ] sxx variance formula
[ S_xx = \sum_i=1^n (x_i - \barx)^2 ]
[ \widehat\mathrmVar(S_xx) = \frac2 S_xx^2n-1 ] [ S_xx = \sum_i=1^n (x_i - \barx)^2 =
Variance of a chi-squared random variable with (k) df is (2k): sxx variance formula
[ \frac(n-1)s_x^2\sigma_x^2 \sim \chi^2_n-1 ]
It seems you’re looking for a paper or derivation related to the term — a common notation in statistics, particularly in simple linear regression and sum of squares decomposition .