Tuesday, July 17, 2012

Pass Accuracy and Possession Supremacy At Euro 2012

With Spain's (and Barcelona's) successes in recent years, possession is one of those concepts that people have been spending a lot of time talking about - though what exactly possession is or how it should be measured is less clear. In the post below, Andrew Brocker takes a look at two dimensions of possession-based analyses: the amount of possession and pass accuracy. Do they matter? Well, taking a look at the data below, the success of Spain and Germany in the tournament suggest so, but Russia and Netherlands suggest not .... You be the judge!

Pass Accuracy and Possession Supremacy At Euro 2012
By Andrew Brocker

With Euro 2012 in the books and another trophy lifted by the possession and pass happy Spanish team, let's take a look at the possession and pass accuracy statistics for each team that competed in the tournament.*

The chart above shows the relationship between each team's average ball possession and pass accuracy during the tournament. Along the vertical axis we see the plus/minus average share of ball possession, while along the horizontal axis we see the plus/minus average pass accuracy. The first thing we can note is that no team with an average inferior passing accuracy managed to enjoy an average superior share of ball possession.

In the top right quadrant we can see that seven teams at Euro 2012 had both a positive share of average ball possession as well as a higher average passing accuracy than their opponents. As we might have expected, Spain exceeded their opponents in both categories, averaging just over 12% greater pass accuracy than their opponents during their six Euro 2012 matches and as a result enjoying almost 32% greater possession (66 to 34). Of the remaining six teams in the top right quadrant, three failed to reach the knock-out stage, those being Russia, Netherlands and the Ukraine while finalists Italy, semi-finalists Germany and quarter-finalists France also achieved greater average ball possession.

In the bottom left quadrant we find the teams that averaged less possession time than their opponents as a result of an inferior passing accuracy. Four of these teams managed to reach the knock-out stage, these being semi-finalists Portugal and quarter-finalists England, Greece and the Czech Republic. Portugal were a penalty shoot-out away from an appearance in the final despite averaging an inferior pass accuracy of 5% and -12.4% less average ball possession (43.8 to 56.2) . Meanwhile England's quarter-final appearance can perhaps be regarded as fortunate considering they averaged 20 minutes less ball possession (40 to 60) than their opponents as a result of an inferior average passing accuracy of -6.75%. As might have been expected Ireland posted the worst numbers for average ball possession and pass accuracy through their 3 tournament matches, seeing 32% less average ball possession (34 to 66) from an inferior average pass accuracy of -15.33%.

Overall, teams could expect 2.691% average greater ball possession for every 1% superior passing accuracy through the tournament. I.e On average a team that had an average passing accuracy of 85% to 80% (+5%) could have expected to see a superior ball possession of +13.46% (56.7 to 43.3).

* The stats are from WhoScored.com.

Link : www.bettingexpert.com/blog/
Twitter : @AndrewBexpert

Saturday, July 14, 2012

Height Discrimination In Football: Are Referees Biased Against The Taller Lads?

Next time you see Peter Crouch complaining about a referee’s call, you may want to consider these findings from a study by two Dutch academics. Though a couple of years old, it’s one of the more interesting pieces of academic research I have come across recently. In a study titled "How embodied cognitions affect judgments: Height-related attribution bias in football foul calls" the authors (van Quaquebeke and Giessner) examine the decisions referees make – in particular the kinds of biased decisions they can make unconsciously.

(c) Maurice Frazer

Their premise is simple (and I cite from the paper's abstract):
"Many fouls committed in football (called soccer in some countries) are ambiguous, and there is no objective way of determining who is the “true” perpetrator or the “true” victim. Consequently, fans as well as referees often rely on a variety of decision cues when judging such foul situations."
So far so good: in the heat of the match, there are many potential calls referees can make, and they have to choose in a split-second who did what even when the situation isn't completely clear-cut. So how do they judge what happened? van Quaquebeke and Giessner, the study’s authors, think that among other things referees use a player's physical characteristics as a shortcut to determine perpetrator and victim:
"Based on embodiment research, which links perceptions of height to concepts of strength, power, and aggression, we argue that height is going to be one of the decision cues used. As a result, people are more likely to attribute a foul in an ambiguous tackle situation to the taller of two players."
In other words, when in doubt, call the foul on the taller lad.

But could this really be?