$\frac{\hat{\beta} - \hat{\beta}_{(i)}}{se(\hat{\beta}_{(i)})}$

$\frac{\hat{\beta} - \hat{\beta}_{(i)}}{se(\hat{\beta})}$

$\sum_{j=1}^n (\hat{y}_j - \hat{y}_{j(i)})^2$

$\sqrt{\frac{(h_{ii} e_i^2)}{(1-h_{ii})^2 p MSE}}$