nag_stat_prob_students_t (g01ebc) Example Program Results t df prob tail 0.850 20.000 0.7973 Nag_LowerTail 0.850 20.000 0.4054 Nag_TwoTailSignif 0.850 20.000 0.5946 Nag_TwoTailConfid 0.850 20.000 0.2027 Nag_UpperTail