Which European league is hardest to predict?

Italy - Serie B is the hardest league in Europe to call: the favourite wins just 44.8% of the time. At the other end, the favourite in Portugal - Primeira Liga wins 56.5%, a gap of 11.7 percentage points. Italy - Serie B also produces the most draws anywhere in this sample: 31.6% of its matches end level.

Rank Europe's top flights against each other and most of the ordering is noise: of the 55 possible pairings, only 12 separate at the 95% level, and those are the extremes. The division gap is a different kind of number. It is 6.4 points, give or take 0.9, which is bigger than the entire 4.5-point spread across the top flights, and measured tightly enough that nothing about it is in doubt. Which division you are watching tells you more about how predictable the football will be than which country you are watching it in.

The likeliest reason is squad depth rather than anything romantic about lower-league football. A top flight contains a handful of clubs that can afford to be reliably better than everyone else; a second tier is a flatter distribution, and a flatter distribution produces more matches the market cannot separate.

Most of the ordering among top divisions is not real. Of the 55 possible pairings of Europe's top flights, 43 sit inside the margin of error, so for those pairs we cannot say one is harder to predict than the other. The 12 that do separate are the extremes of that group rather than neighbours in the table. Read the top-flight ranking as a rough banding, not a league table: the gap between 4th and 8th on this measure is noise.

None of this is a betting edge either. The calibration table shows where the market's prices sit against results once the margin is stripped out, and that margin is not stripped out of the price anyone is actually offered.

Coverage is a limit worth stating plainly: closing prices are available for 22 leagues in 11 countries, so this is a study of Europe's most heavily priced competitions, not of every league in Europe.

The Predictability Index is the share of a league's matches won by the market favourite: higher means the favourite is more often right, lower means the league is harder to call.

For every settled match carrying an average closing 1X2 price, we removed the bookmaker margin (normalising the three implied probabilities to sum to 1), took the shortest price as the favourite, and recorded whether that selection won. The market is the benchmark rather than our own model on purpose: it is the best information publicly available before kick-off, and using it means this measures the sport rather than grading our own homework.

Every figure on this page describes the same set of matches. Leagues with fewer than 400 priced matches are excluded, as are the matches where the two shortest prices are identical and there is therefore no favourite. Probability bands holding fewer than 300 selections, and part-seasons of fewer than 3,000 matches, are not plotted. Confidence intervals are the normal approximation at 95%.

Closing prices come from football-data.co.uk, whose historical odds archive is what makes a study on this timescale possible at all. Results, fixtures and match statistics are our own.