Log normal distribution of gonadotropins and ovarian steroid values in the normal menstrual cycle.

In the statistical analysis of the values of luteinizing hormone, follicle-stimulating hormone, estradiol, and progesterone obtained from normal menstrual cycles, a depature from normality was noted. Chi square, W test, and linear transformation were used to check the normality of the distributions. The results of this investigation showed that the distributions were not normal (Gaussian) but log-normal. By plotting the probit of the percentages of cumulative frequency on a log scale (probit-log), linearity of the data was obtained. This resulted in direct graphical estimations of values with a useful clinical range, which included the mean and the 95 per cent confidence interval.