Hmm, I imagine that math has its place in estimating male to female results, but the environmental factors which are able to be reasonably controled especially in the winter months are a better determiner on sex results IMO. The RNA which is a plant DNA determines the sex in the plant, this takes place in the first 10 to 21 days, meaning, the sex is determined already durring that period. One simple way to promote more female plants is to keep the temps in the low to mid 60's. Higher temps will produce more males. Don't get freaky with nutes, or tweek out the seedling with a bunch of ruff handling and have nice gentle air exchange and you can increase your chances.
Adieu