This chapter describes commands that fit models (FIT), specify options used to control the fitting process and output (FITOPT), carry out various hypothesis tests (CI, BOUNDS, SCORE, NULL and LRT), and compute various statistics or plots related to a specific fit (BACK, FV, EXCESS, HAT, RESIDUAL, STAT, SCURV, and SETS). Please note that the commands used to compute statistics related to a fit are specific to certain programs.