Use of a confirmed mathematical method for back-analysis of IELT distributions: ejaculation time differences between two continents and between continents and men with lifelong premature ejaculation (Part 1).

Recently it was shown that a stopwatch-measured IELT distribution can be transformed to a mathematical formula of a specific mathematical type distribution. The IELT distribution of men in the general population is a Lognormal distribution whereas that of Caucasian men with lifelong premature ejaculation (PE) is a Gumbel Max distribution. In this article, we developed the mathematical formula of the IELT distribution of two other previously published stopwatch-mediated IELT studies in the general male population of the USA and Europe, respectively, by investigating the fitness of various well-known mathematical probability density distributions into the IELT distribution of the two studies. The better the fitness the lower is the goodnes of fit (GOF). We found that the lognormal distribution most accurately fitted the IELT distribution of 1405 men in the general population of the USA, and 1026 men in the general population of Europe, with a GOF of 0.056 and 0.061, respectively. The current study also shows that the Lognormal IELT distribution of two European studies in Caucasian males are quite similar but that the Lognormal IELT distribution of men in the USA deviates compared to the two European IELT distributions. As the USA study also included 25% of non-Caucasian males it may be speculated that ethnical factors play a role in this deviation of the IELT curve. In conclusion, the Lognormal distribution of the IELT distribution in USA and European general male populations reconfirms our previous finding of a Lognormal IELT distribution in two random samples of the general male population in four European countries and USA. The Lognormal IELT distributions of the general male population highly contrasts to the Gumbel Max IELT distribution in Caucasian males with lifelong PE, as has previously been found.