Closing line value with Pinnacle closing odds

Closing line value compares the odds you took with the last price before the start. Beating Pinnacle's closing line consistently is the best-known sign that bets have positive expected value, long before results can show it.

Computing it fairly

Compare against the fair closing price, with the bookmaker's margin removed. If you took 2.10 and Pinnacle closed at 1.95 / 1.95 on a two-way market, the fair closing price is 2.00 and your CLV is 2.10 / 2.00 − 1 = +5%.

There are several ways to remove the margin. Multiplicative is the simplest; power and Shin handle favourite–longshot bias better. oddssea returns fair prices by any of them (devig=multiplicative | additive | power | shin).

Getting Pinnacle's closing prices

oddssea keeps each line's opening and closing prices for a year. The closing price is the last prematch price before the scheduled start:

curl -H "X-API-Key: $KEY" "https://api.oddssea.dev/v1/opening-closing?event=1637396142"

Each line comes with its opening and closing prices. For the whole path in between, every price move is in /v1/history for 7 days after the start. Record the event id when you bet, look up its closing price after kick-off, and your CLV is one division.

The Prematch plan is enough for CLV: closing prices are prematch prices. Plans.