The other day, in a blog post I mentioned how mutations aren't all that likely. Well, I suppose that the odds are about 16% per skill roll. So, I found myself wondering - how many skill rolls would a team need before they'd be 'guaranteed' (heh!) a double? And after X skill rolls, how many doubles should I expect? Warning: unvalidated stats follow...



This graph shows the probability distribution for getting a number of doubles, given a number of skill rolls (Oh, and excluding +ST. You'd always take +ST, right?) Each of the lines is a probability distribution for a number of rolls. Therefore, if you get another 24 skills (Orange Line), you've got about a 20% chance of getting 2 doubles, and a 24% chance of getting 3 doubles. Or, if you get another 12 skill rolls (Green Line), there's a 16% chance of not getting any doubles at all...

Note that that is skills beyond where you are - each roll is independent, so even if you've had 99 normal skill rolls, these probabilities remain true.

I've gotta admit, I was quite surprised - I kind of thought doubles were much more common, even if I knew the percentages. Still, it matches what I'm seeing in my own teams - after 99 I've got 14 doubles, which is pretty much in the middle of the '99 Skill' curve.