Mar 05, 2016

A bet against Sanders, II

While checking my PredictIt account this morning, I saw that the market was valuing Sanders' chance of winning the presidency at 10%.

Sanders wins presidency

(I took this screenshot after purchasing my shares, which moved the market, so the image is slightly out of sync with the narrative.)

This seemed high to me, so I took a look at the conditional probability of Sanders winning the presidency given winning the Democratic nomination, p(Sanders prez | dnom), the same thing I did for my initial bet against Sanders.

Looking at the Democratic nomination market:

Sanders wins presidency

Sanders is at 17% to win the nomination. So, the conditional probability of Sanders winning the presidency, given the nomination, is:

p(Sanders prez | dnom) = 0.1 / 0.17 = 0.588

A 58.8% chance of winning the presidency if Sanders gets the nomination? That still seems quite high.

So I bought some more "No" shares. My initial bet had done quite well during February, but I had been selling off shares to pay for other bets I wanted to take, so this was a welcome chance to re-up on a bet I feel good about.

[reread: 1, edits: phrasing tweaks]