How the sims earn trust
Three steps from market prices to a posted slip, and how we check our own work.
Real market prices
Every leg starts from Kalshi's public prices. Where a player isn't listed yet, our own usage model prices him from his share of targets and carries.
How legs move together
QB yards, his WR1's catches, the total and the margin are linked using three seasons of nflverse box scores, so stacked slips get credit for going together.
10,000 games a night
Each game is simulated 10,000 times. A slip's hit rate is how many of those games it cashes, compared with what the price needs.
Graded against real results
Kalshi prices from about 90 minutes before kickoff in 77 games already played. Across all parlays and on 2- and 3-leg slips, our sims land closer to what happened than treating legs as unrelated. On 4-leg and same-player slips both sit within half a point.
| Slip type | Slips | Actually hit | Our sims said | Legs treated as unrelated |
|---|---|---|---|---|
| All parlays | 21,732 | 12.3% | 12.0%0.3 pts off | 11.8%0.5 pts off |
| 2-leg | 9,060 | 20.3% | 19.9%0.5 pts off | 19.9%0.5 pts off |
| 3-leg | 7,660 | 8.6% | 8.2%0.5 pts off | 7.9%0.7 pts off |
| 4-leg | 5,012 | 3.2% | 3.5%0.3 pts off | 3.1%0.1 pts off |
| Same player | 3,120 | 7.6% | 8.1%0.6 pts off | 7.5%0.1 pts off |
Glossary
Hit rate
How often a slip cashes across our 10,000 simulated games. 17.7% means it won in about 1,770 of them.
Break-even (needs)
How often a slip has to hit for the price to be fair. At +1039 you need it to win 8.8% of the time just to break even over the long run.
Edge
Hit rate minus break-even, in percentage points. Positive means the price pays more than the slip's real chance deserves.
Fair price
The odds that would make a bet exactly break even given our hit rate. If the book pays more than fair, that's value.
Expected value (EV)
What a bet returns on average over many tries. +10% EV means 1.1u back for every 1u staked in the long run, with lots of variance along the way.
Correlation
Legs that move together, like a QB's yards and his top receiver's catches. Same-game parlays live and die on it, and books price it in.
Units
Our stake size. 1u is a standard bet; most people make it 1% of their bankroll. We size by hit chance: 1u at 40%+, 0.5u at 20-40%, 0.25u at 8-20% and 0.1u on long shots. Everything is tracked in units so it reads the same whatever your bet size.
CLV
Closing line value: whether the price we posted beat the price at kickoff. Beating the close is the best long-run sign of real edge.
Lotto
A long shot we post because the price is too big, not because it's likely. Small stakes only.