Price review guide · A. N. Edvardsen

Closing line value.
What does it tell you?

Closing line value, usually shortened to CLV, compares the price you took with a later reference price near the start of an event. It can help you review your price-taking before results have had enough time to become informative.

A simple back-bet example

Suppose you take decimal odds of 2.20 and the same selection closes at 2.00. A simple raw price-ratio measure is:

CLV = odds taken / closing odds − 1

Here, 2.20 / 2.00 − 1 = 0.10, or +10%. You obtained a higher back price than the closing reference. If you took 1.90 and it closed at 2.00, the same measure would be −5%.

That +10% is a price comparison. It is not a claim that the bet had a true 10% expected return. The closing market may contain margin, and it may be wrong.

Lay bets run in the other direction

For a lay bet, a lower price is preferable because it reduces liability for the same quoted lay stake. One direction-adjusted raw measure is:

Lay CLV = closing odds / odds laid − 1

Laying at 2.00 before a close of 2.20 gives +10% by this convention. Different products use different CLV definitions, so check the formula before comparing percentages across trackers.

Compare the same contract

The selection, handicap, settlement rules and participation terms must match. A price with a different handicap is not a closing price for the original bet. Tennis retirement rules, racing deductions, commission and liquidity can also change what a quoted price means.

Choose a reference source and collection time you can apply consistently. Record missing prices as missing, not as zero CLV. Keep the price you actually obtained separate from the price you intended to take.

Use CLV alongside the rest of the record

Repeatedly beating a useful closing reference is worth investigating. It is not a substitute for checking costs, execution, profitability and whether your bets are independent. Thin or inefficient markets may have a less reliable close.

If you estimate your own probabilities, calibration asks a different question: do outcomes occur at approximately the frequencies you forecast? A Brier score summarises forecast accuracy. Neither metric establishes an edge on its own.