Certain approximations, commonly used in the "one-hit" statistical analysis of radiation data in terms of size, shape, and sensitivity of macromolecules, are discussed quantitatively. It was shown that the current approximation procedure of comparing radiation data which obtain for different radiations, is usually accurate to within a few per cent. Variation in the observed cross section with radiation dose, which is sometimes to be expected on theoretical grounds, was discussed, as was the feasibility of comparing, in such cases, the results obtained with different radiations. Tables and formulas are given which may be useful for analyzing experimental results. Effect of delta-rays was included in the quantitative discussion.