Predictor uses the p-value of the partial F statistic to determine if a stepwise regression needs to be stopped after an iteration. ANOVA (analysis of variance) statistics for standard regression with a constant:
For addition of a variable, the partial F statistic for step t, (PFt):

PFt follows the F distribution with degrees of freedom equal to (1, Error DF at step t). Users provide a maximum p-value, below which the variable is added to the regression.
For deletion of a variable, the partial F statistic for step t, (PFt):

PFt follows the F distribution with degrees of freedom equal to (1, Error DF at step t). Users provide a maximum p-value, above which the variable is removed from the regression.