deletions | additions       diff --git a/Computing_this_within_class_variance__.tex b/Computing_this_within_class_variance__.tex  index 1779225..4fb0581 100644  --- a/Computing_this_within_class_variance__.tex  +++ b/Computing_this_within_class_variance__.tex 
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If you subtract the within-class variance of the combined distribution, you get something called the between-class variance:  \begin{align} \begin{align*}  \sigma_{\text{Between}}(T) &= \sigma^2 - \sigma^2_{\text{Within}}(T) \\  & = n_B(T)[\mu_B(T)-\mu]^2+n_O(T)[\mu_O(T)-\mu]^2  \end{align}