Revisiting the invisible leprechaun hand

Faithful readers of this blog will remember that I lost a memorable hand to a straight flush a while back, which I wrote about in the "Invisible leprechauns" post. At the time, I guessed my chances of losing in that situation were only about 1%. Using an online poker odds calculator the next day, I discovered that the actual number was considerably higher -- namely, 8.28%. I then tried working out the odds on paper to verify the number, but came up with 9.19% instead.

Recently, I decided it would be beneficial to write my own odds calculator, since I could tailor it any way I saw fit. This weekend, I finished it, and it also came up with the 8.28% number. Here's the breakdown of opponent hand types which beat my hand, out of a total of 990 possible turn and river combinations:

straight: 45
flush: 33
four of a kind: 1
straight flush: 2
royal flush: 1

(45 + 33 + 1 + 2 + 1) / 990 = 82 / 990 = 8.28%

When I tried working the odds out on paper, my mistake was crediting too many flush wins to my opponent; what I forgot about was that any flush my opponent made with the 3 of diamonds would actually lose to my hand, since in that case I'd have a full house of queens over threes. I'd been erroneously crediting my opponent with 42 flush wins instead of 33; that produced the faulty 9.19% number.

The upshot of all this is that I was indeed the victim of a suckout on that hand, but the suckout was not of quite as monstrous a proportion as I'd guessed in the heat of the moment.

On Friday night, I porpoised around, but ended up with a modest gain.

delta: $16,800
balance: $590,714