Sxx Variance Formula Official

[ S_xx = \sum_i=1^n (x_i - \barx)^2 = (n-1) s_x^2 ]

[ \mathrmVar(\hat\beta 1) = \frac\sigma^2S xx ] sxx variance formula

If (x_i \sim \texti.i.d. N(\mu_x, \sigma_x^2)): [ S_xx = \sum_i=1^n (x_i - \barx)^2 =

[ \frac(n-1)s_x^2\sigma_x^2 \sim \chi^2_n-1 ] sxx variance formula

Thus:

[ \mathrmVar(S_xx) = 2(n-1)\sigma_x^4 ] We know:

Therefore: