1. A method for implementing a level bias function for branch prediction control for generating test simulation vectors comprising the steps of: receiving user selected options for a set of constraints for generating test simulation vectors for branch conditional instructions; reading current resource values for predicting a branch for a branch conditional instruction; and generating a branch operand field BO to include a set of valid values using said current resource values and based upon said user selected constraints; said branch operand field BO defining conditions under which a branch is taken.