$$ S_b\;=\;\int E(z)z^2dz $$latex \hat{f}\left(\bar{x}\right)=\theta_{o}+\theta_f{1}{\bar{x}}_\mathbf{1}+\theta_\mathbf{2}{\bar{x}}_\mathbf{2}+{\ldots}+\theta_{k}(1)
//väri
$$ S_b\;=\;\int E(z)z^2dz $$
