Monday, July 14, 2014

Harald's Original Miscellany - More Truth about Football - Part 4

Finally, Germany has won the Soccer Worldcup 2014. Therefore, also our little statistics on soccer will come to an end with the post today. You might ask yourself what kind of data is left for soccer players in Wikipedia and DBpedia. Well, unfortunately only a little. But, we will try to make something out of it. Last time, we've ask for the number of team changes and the correlation to popularity vs. scored goals for soccer players. What is left, if we look at the available data?





We have the data about the years in which the football players were active or have played in their national soccer team. Let's start with the national team years [1]:

nationalyears NumPlayers
8 3
7 20
6 85
5 371
4 1070
3 2479
2 6116
1 28211

Well, it was obvious that the most players have only 1 or two years in the national team. But, there are exceptional players who achieved even 8 years. But, who are these long term players? [2]:

nationalyears Player Team
8 Wojciech Łobodziński "Poland"@en
8 Wojciech Łobodziński "Poland Under 16"@en
8 Wojciech Łobodziński "Poland Under 17"@en
8 Wojciech Łobodziński "Poland Under 21"@en
8 Wojciech Łobodziński "Poland Under 18"@en
8 Santiago Cañizares "Spain Under-17"@en
8 Santiago Cañizares "Spain Under-16"@en
8 Santiago Cañizares "Spain Under-21"@en
8 Santiago Cañizares "Spain Under-18"@en
8 Santiago Cañizares "Spain Under-23"@en
8 Santiago Cañizares "Spain Under-19"@en
8 Santiago Cañizares "Spain Under-20"@en
7 Aydın Yılmaz "Turkey Under-21"@en
7 Aydın Yılmaz "Turkey"@en
7 Aydın Yılmaz "Turkey"@en
7 Aydın Yılmaz "Turkey Under-19s"@en
7 Aydın Yılmaz "Turkey Under-17"@en
7 Aydın Yılmaz "Turkey A2"@en
7 Ismael Urzaiz "Spain Under-17"@en
7 Ismael Urzaiz "Spain Under-16"@en

Possibly you will never have heard of Poland's Wojciech Łobodziński or Spain's Santiago Cañizares. Here another flaw in the data becomes visible. There is no such thing as the unique national team. We have "under 16", "under 17", "under 18", and so on... So you start your career already with 15 and after 8 years you would be 23 and possibly be in the "real" national team.

Let's have a look at the active years of players. Unfortunately, here the data is rather messy [3]: 
person From To
http://dbpedia.org/resource/Marta_(footballer) 2000 9223372036854775807
http://dbpedia.org/resource/Carlos_Alberto_Gomes_de_Lima 2006 200720082008
http://dbpedia.org/resource/Blake_Camp 2008 200420052006
http://dbpedia.org/resource/Birgit_Prinz 1998 200320042005
http://dbpedia.org/resource/Dejan_Damjanovi%C4%87 1998 20112012
http://dbpedia.org/resource/Inka_Grings 1995 20092010
http://dbpedia.org/resource/Breno_Silva 2003 20092010
http://dbpedia.org/resource/Vin%C3%ADcius_Calamari 2007 20092010
http://dbpedia.org/resource/Samuel_Jos%C3%A9_da_Silva_Vieira 1994 20082009
http://dbpedia.org/resource/Chad_Marshall 2004 20082009
http://dbpedia.org/resource/Michael_Parkhurst 2003 20072008
http://dbpedia.org/resource/Geison_Rodrigues_Marrote 2004 20072008
http://dbpedia.org/resource/Dejan_Stankovi%C4%87 1994 20062010
http://dbpedia.org/resource/Glauber_Da_Silva 2001 20062007
http://dbpedia.org/resource/Hugo_Sarmiento 1999 20032007
http://dbpedia.org/resource/Obafemi_Martins 2000 20032004
http://dbpedia.org/resource/Heslley_Couto 2005 20032006
http://dbpedia.org/resource/Dalibor_Filipovi%C4%87 1992 20022003
http://dbpedia.org/resource/Dmytro_Zayko 2005 20022004
http://dbpedia.org/resource/Aviv_Volnerman 1998 20012004

Possibly this is because of people not only writing single year's into the Wikipedia infoboxes, but time spans and other things. In the list above are only the Top 20. Just remove the LIMIT from the SPARQL query and further down you will find more valid data.

OK, let's come to our last problem related to football. Is there a correlation between the height of a player (simply because we have that data) and the number of achieved goals [4]?
Height sumgoals
243.84 1
23.0 59
215.9 1
206.0 0
204.0 0
203.2 24
203.2 47
203.0 0
203.0 0
203.0 51
202.0 19
202.0 0
202.0 15
201.0 20
201.0 0
201.0 0
200.66 11
200.66 48
200.66 0
200.66 0
200.66 0
200.66 124
200.66 146
200.66 0
200.66 1
200.66 16
200.66 0
200.66 102
200.66 6
200.66 0
200.0 0
200.0 20
199.0 0
199.0 0
199.0 78
199.0 47
199.0 0
199.0 62
199.0 32
199.0 84

It is rather difficult to recognize something in this data. You see heights and the number of goals that player of that height have scored. Fascinating that there seem to be a significant number of players that are taller than 2 meters. I guess that the list leader with 2.43 meters is just incorrect data. Now. this is so many data that we have to visualize it to recognize something....

Correlation between height of soccer players and scored goals
In the diagram to the left you see the soccer players height (x-axis) vs. the number of scored goals (y-axis). Interesting thing to notice is that the heights approximately show a Gaussian distribution, i.e most players have a "middle" height, on the extremes there are only a few. Well, there seems to be an exception. on the outer left you will notice a large fraction of players with a height of 1.52m with goal scores ranging among 0 to 300. This is extraordinary, because I have no idea what kind of group this is or if there is simply an error in the data again. What I noticed is that among this group there seems to be a larger fraction of female Asian soccer players. Maybe they are responsible for that large number of outliers, but this requires further investigation.

Alas, I want to add one last table. For each player there is the information on which position she or he is playing. Of course Wikipedia authors are far from any sort of agreement how to name the player's position. Thus, there is a rather huge variety. Nevertheless, I will leave you with the table to make any sense from it. Enjoy [5]:
position number avheight avgoals
midfielder 4450 176.822828644929299 18.077078651685393
defender 3429 181.37523034450506 8.058326042578011
striker 2643 180.169761559433703 65.213015512674991
goalkeeper 2086 186.186064557569709 0.174496644295302
forward 1787 178.865346269495465 46.388919977616116
centre back 786 185.7391350821381 10.651399491094148
winger 648 174.69354896725695 27.583333333333333
attacking midfielder 490 175.897877222177931 38.006122448979592
left back 461 177.661735253323698 6.995661605206074
defensive midfielder 427 179.741452037869347 11.978922716627635
right back 405 177.829456545982828 7.301234567901235
central defender 196 185.005408462213008 8.897959183673469
central midfielder 161 178.223105294363834 20.099378881987578
full back 158 174.659366173080242 6.759493670886076
centre forward 140 179.09685701642717 80.792857142857143
left winger 113 174.790176753449224 28.398230088495575
defender, midfielder 102 179.789412255380659 10.607843137254902
inside forward 96 172.094789346059145 64.083333333333333
defender/midfielder 82 179.178292995545911 11.463414634146341
defender / midfielder 79 180.188100887250282 15.050632911392405
left-back 65 175.642922504131603 7.692307692307692
right winger 62 175.247418803553424 30.096774193548387
centre-back 56 521.327500479561941 9.375
right-back 54 176.101110952871815 6.111111111111111
midfielder/forward 52 172.013075924836657 22.557692307692308
midfield 52 176.982691251314588 30.673076923076923
defender (retired) 50 181.37344055175781 14.48
second striker 48 174.673332850138346 63.854166666666667
full-back 44 175.908408771861666 2.681818181818182
striker / winger 41 178.235609845417295 49.219512195121951

Of course I limited the table to 30 rows. Interestingly, the average height of goalkeepers is larger than for midfielders or strikers. As expected, strikers on the average score more goals than defenders or goalkeepers.


SPARQL Queries and original data:

No comments: