Frame flexibility and deflection estimates, needed for one or more of a number of purposes in design for seismic resistance, are most usually made from the bending moment diagram and the elastic properties of a column, by the moment area or a related method. (To state the obvious), the assessments thus obtained can only be accurate when the bending moment determinations are precise. It is perhaps less evident that small but tolerable bending moment errors may produce large intolerable deflection errors.