Explained
A margin figure is meaningless without its basis
The same bookmaker can honestly be called the cheapest or the dearest in Ghana, depending on which football somebody priced.
Convert the three prices on a football match back into probabilities and add them up. A perfectly fair book totals one; a real one totals more, and the excess is the margin. It is the bookmaker's charge, it is taken whether you win or lose, and over a season it is most of the difference between a bettor who breaks even and one who does not.
The trap
Every book prices its showcase competition far sharper than the rest of its own football, because that is where its competitors are watching. On this register the same bookmaker has been measured at roughly two per cent on top-flight European football and three times that across all the football it prices. Both figures are real. Only one of them describes the bet most people actually place.
So a margin quoted with no basis attached always flatters whoever quoted it, and the flattering number is the one that ends up in a comparison table. Several records in the fact base behind this site carry an explicit instruction not to print the sharp figure without the words that qualify it, and those instructions are printed on the site alongside the figures.
Why the six figures on this site are not a ranking
They were computed on different things. One is the median across nearly five hundred matches from a bookmaker's own price feed. One is the mean of eight fixtures captured in a browser. One is two matches from a third-party aggregator, because the bookmaker itself served no prices at all to anybody outside the country. Ordering them smallest to largest is fine. Calling the smallest the cheapest book in Ghana is not.
What to do with it
Compare like with like on the competition you actually bet. Open the same fixture at two books and add up the implied probabilities yourself; it takes a minute and it is the only comparison that describes your betting rather than somebody's sample.
Questions this raises
- Is a lower margin always better?
- On the same fixture, yes: it is a straight discount on everything you stake. Across different fixtures it tells you less, because a book can be sharp where you do not bet and wide where you do.
- Why do so few bookmakers here have a measured margin?
- Because most of them do not serve prices to an address outside Ghana, or build the coupon in the browser and serve nothing to anything else. One served a coupon containing fixtures that are not real matches, which is not a published price and was discarded.