AbstractTwo modifications of Sigmund's sputtering formula, viz. by Bohdansky and by Yamamura et al. are compared with an α-adaptation of Sigmund's original formula to 620 experimental sputtering yields taken from literature. Using the α-values for the comparison, it was found that the considerable scatter of these values (averaged for given M₁, Z₁, M₂, Z₂) is not reduced by either of the two modifications, except for values in the range M₂/M₁ > 100. In each of the three versions the scatter is systematic, however, in as far as certain target elements yield average values of α which are consistently high, low or intermediate over a wide range of M₂/M₁ ratios.