It seems to be generally conceded that the results obtained with a photoelectric colorimeter are significant only when the spectral characteristics of the sample and standard are similar. When this is the case, the selected ordinate method of integrating spectrophotometric data can be greatly abridged, a single selected ordinate being adequate under many circumstances. This means that an abridged spectrophotometer can be used for the dual purpose of production control and, when necessary, the determination of tristimulus values.