Normal Distribution -- Applicable to Winrates?

[Collin Moshman]

Hi guys,

It seems that in discussions of poker winrate calculations, it's usually taken for granted that the normal distribution applies. As a typical example, here is an article from this month's 2+2 magazine on SNG ROI calculations:

http://www.twoplustwo.com/magazine/c.../Vork0607.html

Keeping the discussion a bit more qualitative, I don't think this arrows around a bullseye approach works well for poker. As time goes on, your abilities change, as do your opposition, available rake deals, etc. E.g., when I play SNGs, I like to think I'm getting better with time. In that case, basing winrates on a mean parameter would clearly give misleading results. Same with BB/100, other games ... has anyone seen an approach to winrates that relies on other parameters / appeals to other distributions?

Any ideas greatly appreciated.

Best Regards,
Collin