Total sum of squares - Wikipedia
https://en.wikipedia.org/wiki/Total_sum_of_squaresIn statistical data analysis the total sum of squares (TSS or SST) is a quantity that appears as part of a standard way of presenting results of such analyses. For a set of observations , it is defined as the sum over all squared differences between the observations and their overall mean .: For wide classes of linear models, the total sum of squares equals the explained sum of squares plus the residual sum of squares. For a proof of this in the multivariate OLS case, see partitionin…