In recent years there has been a move away from the purely literary to the numerically descriptive medical publications. This is largely attributable to a change in emphasis and direction in the medical sciences as practitioners become more ‘mathematically aware’. Sample populations are often described in terms of numbers, ratios, percentages or rates. All of these descriptors have merit in supporting the expression of methods and results in clinical trials, research and epidemiology. The application of rates can be most useful, particularly as results are not always considered in terms of simple numerical counts, but are often related to an underlying population.