请问这篇关于margin analysis 的文章，
https://www.stata.com/features/overview/marginal-analysis/

这几句分析是怎么算出来的。我怎么看不明白了。谢谢。

“We obtain predictive margins. If the distribution of cigarettes smoked remained the same in the population, but everyone was male, we would expect about 45% to have a positive outcome for y. If everyone were female; 55%. If instead the distribution of males and females were as observed but no one smoked, we would expect about 39% to have a positive outcome.”