A few people missed the reasoning for this post. It is not to increase the odds of getting females, but instead increasing the odds of producing a given number of females.

As the OP says, if you only have room for 2 plants to flower you want 2 females. How many seeds should one start with to give the best odds (within reason once approaching 100%) to have 2 females?

It isn't trying to say you have more/less chance at all/no females, it is just looking at: if you want X females, you should start with Y seeds. The averages will always remain 50/50 on the whole, but planting 10 seeds and wanting 2 females would pretty much be a "guarantee". Is 9 seeds enough for 2 females? How about 7? Etc...