WhatsApp Image 2018-08-11 at 17.00.07
Another 1-1 draw

A few patterns are emerging, after a couple of weeks of forecasting. One is that it’s harder work predicting scores outside the Premier League, but the other is that as scores are individually low probability events, anomalies can arise.
In expanding our model to cope with promotion and relegation, and longer term trends in teams’ strengths, we’re now estimating over more seasons and more divisions. The upshot appears to be that we predict a lot of 1-1 draws. Now, is that a bad thing?
If we look at every single match on the Soccerbase website, we find 11% of matches have finished 1-1 — the most common score ever. With almost every single 1-1 we predict, it’s with a probability of about 11%. So perhaps not the worst thing in the world that our model predicts this quite a lot.
Equally, though, it might be a sign that our model is not really able to distinguish between the kinds of matches that do finish 1-1 and the ones that don’t. It’s all well and good predicting 1-1 every single time, but it’s hardly very insightful.
An alternative is to consider¬†conditional probabilities — probabilities conditional on the most likely result occurring. Now despite 1-1 being the most common score, the most common result is a home win. About 46% of the time, the home team wins, draws only occur about 24% of the time. So a conditional forecast would first determine the most likely result, and then produce as the score forecast the most likely score delivering that particular outcome. In our forecasts for tonight’s games in the National League and EFL Cup, we also produce a column with conditional forecasts.