by Brandon Tan
One of the most discussed statistics in soccer leading up to a match is “league form”: the results of the team’s last six games. We see this statistic referenced again and again by commentators and pundits in their match previews and analyses. The phenomenon is all over the websites of sports news outlets, such as here in the Guardian.
However, is form a statistic that we should care about? Does being “in-form” really predict match outcomes?
To answer this question, I test whether there is a significant correlation between the match outcome and league form. I compiled the fixture results from the English Premier League seasons 2010-11 to 2015-16 for each club and ran a simple linear regression with points earned (Win- 3 points, Draw- 1 point, Loss- 0 points) as the response variable and form (the average points earned over the last six matches) as the explanatory variable controlling for home advantage and the end-of-season rank of the opposing team (see Figure 1).
What I found was that there is no statistically significant correlation (at 5% significance) between points earned and form for any club. For instance, consider the results below from running the regression on Manchester United’s fixtures (see Figure 2). Home advantage and rank are clearly significant with p-values close to zero, while form isn’t even close with a p-value of 0.837, way above the 5% significance necessary to suggest a legitimate prediction model.
Someone might argue that 6-game form is considering too many games, so I tried running the regression on form defined as the average points earned from the last 3 games instead. Again, I found no statistically significant correlations, with the p-value from running the regression on Manchester United fixtures at 0.494.
This analysis suggests that as soccer fans we really need to stop making such a big deal out of form, because it really doesn’t tell us anything at all.
|Team||p-value from regression (form = average points earned from last 6 games)|