Measuring closing line value

Convert the price you took and the price the market closed at into probabilities, then take the difference. Bet at +105, which is 48.8 per cent, and watch it close at −105, which is 51.2 — you beat the close by 2.4 points.

The closing line is the most accurate number the market ever produces, because every opinion that was going to arrive has arrived by then. Consistently getting a better number than the close means you are systematically ahead of the process that produces the most accurate number available.

It is slow. Twenty bets of positive CLV is not evidence of anything, because the noise in your own price selection is larger than the signal over that many observations. Several hundred is where it starts to mean something.

That is also the expensive part. It is not profit and cannot be spent. You can beat the close on every bet of a losing month, and treating CLV as a scoreboard rather than a process check is the most common misuse of the only honest metric available.

What to do with it. Record the price at bet time and the closing price for every bet. It costs nothing and it is the one measurement that survives selective memory.