The factors which influence the accuracy of radio noise measurements can be divided into two classes: namely, those which affect the accuracy of steady-state sine-wave radio-frequency measurements, and those which are peculiar to the nonsinusoidal wave shapes of radio noise. Some of the factors can be controlled by suitable standardization of design specifications and methods of measurement, while other factors are dependent on the characteristics of the wave form and on the point at which it is to be measured. Probably the greatest measurement discrepancies that would be encountered under well-controlled conditions can be attributed to differences in the wave collectors employed and to the variations in charge time "constant" of the metering circuit with differences in noise levels. An extensive analysis of the latter effect is presented.