Where 〖R_k〗^2 is the R^2 obtained when the kth regressor is regressed on the remaining variables. The optimal value for this statistic is 1.0 which occurs when the R^2 is zero, or this variable is orthogonal to the other variables. Some fairly straightforward algebra reveals that, if the model contains a constant term – that is , one of the columns of X is a column of ones – then,