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In hindsight, relegation often seems inevitable. If you had asked the pundits, Blackpool's demotion to the Championship last year was all but a done deal in August. But do the data agree? And what can they tell us about the inevitability and predictability of relegation ahead of time, rather than after the fact?
It's not an easy question to answer. The trick to avoiding what psychologists call hindsight bias is to spot trends before they become facts. But that's a hard thing to do in the middle of a season when the weekly performance of teams varies for all kinds of reasons and the hoopla and grind of the season make it difficult to see the forest - the real performance of a club - for the trees (some examples are here). Moreover, there are so many different and variable data points to consider - match outcomes, individual player form, injuries, you name it - that normal data analysis techniques aren't always ideal for assessing what is really going on. And finally, to avoid seeing relegation as inevitable requires analysts to be on the lookout for early warning signs - but how would we know what those signs might be and when they might show up?
To explore how these challenges can be dealt with, let’s look at what happens to relegated clubs during the course of an entire season with data from 2011-12. Some obvious questions you might ask of the data are these:
- How did relegated clubs perform?
- Were there obvious trends in performance early in the season - did relegated clubs get better or worse over the course of the season?
- Were the trends in performance radically different between relegated and non-relegated clubs?
But enough of the econometrics - how does it look in practice?