BSP (Betfair Starting Price)
The Betfair-exchange-derived starting price, calculated from the orders matched at the moment the traps open. Typically more generous than industry SP.
BSP is the Betfair Starting Price — the decimal odds derived from the exchange's matching algorithm at the moment the race goes off. It represents the clearing price between everyone who wanted to back and everyone who wanted to lay at race start.
Why BSP matters: it's a real, tradable, market-cleared price. On average it clears a few percent more generous than industry SP, after Betfair's commission. For settled-historic analysis, BSP is the cleanest "what price was available" reference.
In TrapStats: BSP is one of the SP sources we track per race entry, drawn from Betfair historical data. For comparing model predictions against a realistic available price after the fact, BSP is typically the closest proxy. But for a forward-looking selection decision, only the forecast price (or live exchange back-price) is valid — BSP is post-finish information and using it pre-race is a temporal leak.