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Referees, Assistants, Videos, and Human Error

13/2/2023

 
By John Considine
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Linesmen.  These were two soccer officials that ran along the sidelines of the field in line with the last defender (excluding the goalkeeper).  They were usually men and their main job was to raise a flag to signal if a player was in a position prohibited by the laws of the game.  Now the word, and the many of the human functions, are effectively obsolete.
 
As women started to perform the role, the “men” part was never going to survive in the 21st century.  If the Church of England are considering renaming the “Our Father” then “Linesmen” never stood a prayer.  The artists previously known as Linesmen became known as Assistant Referees.  Soon they will be replaced by symbols.  There are still two humans who perform a variation of the same physical acts.  They run, reason, and raise their flags.  But they don’t really matter.  They have been replaced by a higher power - a human who interprets images from cameras.  When it comes to important offside decisions the Video Assistant Referee (VAR) is all that matters.  Soon, even that human will no longer be needed – player location is a small problem compared to the location technology that is already used by driverless cars.  I regard such changes as progress.  Events of the last few days will hasten the demise of the human VAR.  Human error in the implementation of VAR might have costs Arsenal and Brighton two points each.
 
Since the introduction of VAR, and the change in guidelines to the two human assistant referees, there has been an 11.3% decrease in the number of offsides.  This number comes from a welcome addition to the growing research on VAR.  It is from a SSRN paper by Camilo Abbate, Jeffrey Cross and Richard Uhrig (the latter two authors have Journal of Sports Economics paper on the impact of Covid-19).  The SSRN paper uses observations from 35,183 games from the 16 top leagues.  It is primarily concerned with home-field advantage.
 
Like the humans patrolling the sidelines of soccer fields, the last paragraph of the SSRN paper raises a flag about a potential problem.  The flag relates to the conventional wisdom in sports economics that the (main?) channel for home-field advantage is referee bias.  Interpreting the lack of statistical support for referee bias, the authors say “One must consider the possibility that the observed disparities in various outcomes … are driven by the direct effect of fans on players rather than the referee”.  A worthy consideration.  Although the referee makes the ultimate adjudication on whether of not there is foul play, the play itself is the product of the players.  If there are human errors and biases, that arise as the result of mass psychology, then it is worth considering if they are the product of 22 biological machines rather than just one.

Salary determination in professional football: empirical evidence from goalkeepers

10/2/2023

 
By David Butler

In football, the market for goalkeepers is exclusive. Recruiters tend not to invest equivalent transfer fees on goalkeepers relative to other positions and goalkeepers are also paid less than outfield players. But a relatively undisputed view is that first-rate goalkeepers are critical to team success - it seems paradoxical that fewer financial resources are dedicated to the position.

With colleagues internationally, we have begun to consider these issues and last week published a new paper on ‘Salary determination in professional football: empirical evidence from goalkeepers’ in the European Sport Management Quarterly.

In this paper, we test the determinants of goalkeeper pay and discuss if football clubs effectively separate goalkeeper performances from outfield players. Goalkeepers after all should be evaluated on their own performance, not on that of those around them.

We use a new goalkeeper salary dataset from Capology and match this with basic and advanced performance measures produced by Statsbomb.

What do we find?  Clubs use primitive defensive statistics to determine goalkeeper pay. Counter-intuitively, we fail to find evidence that goalkeepers who save more shots get paid more and goalkeepers are not remunerated for their direct defensive contributions. Team outcomes rather than goalkeeper performance seems to be critical to their pay, despite the presence of advanced stats that allow goalkeepers ability to be individually appraised such as post shot expected goals.
​
Maybe the most interesting result is the importance of goalkeeper’s passing success for salary determination. The labour market rewards goalkeepers who are better than others at contributing to their team’s offensive moves – modern goalkeepers are now the first line of attack!

The Oracle vs The Market

8/2/2023

 
By David Butler

Over Christmas I got a chance to watch more football than usual. One innovation I spotted from Sky was how they now present Win Probabilities - powered by Oracle Cloud - as a match progresses. According to official website, these probabilities are calculated “using four years of match data, [and] shows the chance a team will win or draw by simulating the remainder of the match 100,000 times”

I was interested to see how the forecasts matched up with market odds. For the case below - Brentford vs Tottenham, I checked the betting markets the very second the win probabilities were presented by Sky.

There were differences. Controlling for the bookmakers take, there was ~18% chance of Brentford success. The bookies estimated a draw to have a ~55% chance and had a Tottenham win at ~27%. 
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ESEA Keynote Speaker 2 - Professor Alex Bryson

7/2/2023

 
By Robbie Butler

The 14th European Sport Economics Association (ESEA) Conference will be held at University College Cork, Ireland from the 23rd to the 25th of August 2023.

We are delighted to announce the event will include a keynote address by Professor Alex Bryson of (IZA Institute of Labor Economics) University College London (UCL).

Prof. Bryson is Professor of Quantitative Social Science at UCL's Social Research Institute. He joined IZA as a Research Fellow in July 2014. He is also a Research Fellow at the National Institute of Economic and Social Research (London) and a Rutgers Research Faculty Fellow.

His research focuses on industrial relations, labour economics and programme evaluation. Prof. Bryson is Editor-in-Chief at Industrial Relations: A Journal of Economy and Society and an editor of the Journal of the Royal Statistical Society: Series A and the Journal of Participation and Employee Ownership.

His sports economics work is widely read and cited. He has published papers on superstar effects, coaching performance and the impact of Covid-19 on sport, and is a member of the Erasmus Centre for Applied Sports Economics (ECASE) Scientific Board. Many of his papers are published in ABS 3* and ABS 4* journal, as well as the leading journal in our field, the Journal of Sports Economics.

​Those wishing to attend the conference should know that submissions are welcome relating to any area of sports economics including theoretical, empirical and conceptual papers.

Please submit an extended abstract including introduction, theoretical background, methods and major finding via the submission portal that can be found on the conference website: www.cubsucc.com/esea-call-for-papers.

Abstract submission deadline: 31st March 2023.
Notification of acceptance: 30th April 2023

Full information about Cork 2023 can be found on the event website: www.cubsucc.com/esea-home/

Investment Alternatives and the Women's Super League

2/2/2023

 
By John Considine
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In late January, a game between Chelsea and Liverpool in the Women's Super League was abandoned after six minutes.  The decision to play the game on a frozen pitch seemed strange.  The various media outlet had a field day discussing the issue, e.g. here is Sky Sports' "The Football Show" discussing the issue.  There was growing support for the idea that WSL grounds needed undersoil heating.  Some of the contributions to the debate would have been at home in Trekonomics: The Economics of Star Trek.

In Trekonomics Manu Saadia discusses the difference between the virtual world of the space ship's holodeck and the real world.  Scarcity and trade-offs do not feature prominently in the holodeck.  You can build your own world.  Perfect grounds.  Perfect weather.  That is not the world faced by the WSL.  It is not even the world faced by the Premier League.  Resources are scarce.  A more consider view of the situation came from the Arsenal manager.  Jonas Eidevall said "We need to take good decisions on where the investment should be going to grow the game in the long term and I'm very doubtful that should be put into undersoil heating at the moment".  There are plenty of needs/wants and limited resources.  It is important that they are put to best use.

Diversification and Goals in the Premier League: Man City vs Arsenal

1/2/2023

 
By Daragh O'Leary

Diversification is a topic which is brought up frequently in economics. Investors often advocate diversifying portfolios to protect themselves against shocks to certain industries. Put more simply, this means it’s wise not to put all your eggs in one basket. Last weekend, I found myself wondering was this a mistake that Pep Guardiola has made.
 
Manchester City have acquired probably the best out-and-out centre forward in the world. Maybe Erling Haaland hasn’t got the most well-rounded game in terms of dribbling and skill, but he is undeniably a phenomenal goal scorer. The Norwegian now has 25 Premier League goals after just 19 appearances. Meaning he is averaging 1.32 goals a game and quite good at football. Despite this amazing stat, Man City are worse off this year than they were last year.
 
After 20 matches last year Guardiola’s men sat at the top of the table with 50 points. This year after the same number of matches they find themselves in 2nd place with just 45 points. Meaning they are 5 points behind the league leaders Arsenal who have played a game less.
 
How have they managed that?
 
As a boyhood Arsenal fan, I would love to think this is all because of Mikel Arteta and Arsenal. However, considering Arsenal are yet to play Manchester City this can hardly be the case. I think the answer could be the transition of Man City from a team with a lot of goal scorers, to a team with one player who can score a lot of goals. The below graph illustrates the latter.
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Haaland has scored just over 47% of Manchester City’s 53 Premier League goals. That’s nearly every second one. Their second highest scorer is Phil Foden with just 7 goals (13.21%). An issue which arises with such an over-reliance on one player is that if he gets injured or goes through a bad patch of form, nearly half of your goals are gone. Additionally, there has been games this season where Haaland has played and scored, but not scored enough to win the game. City’s draws to Everton and Villa are good examples of this. In years gone by, I don’t think this would have been an issue for Man City.
 
During the 2017/18 season Pep’s men became the first ever Premier League centurions. They managed to accumulate 100 points in one season. That season Manchester City’s highest scorer finished 11 goals behind the Golden Boot winner. The reason this didn’t matter was because 4 different players for City all scored 10 goals or more. If an opponent could stop Aguero, then Sterling, Jesus and Sane could step in. This doesn’t seem to be the case for Man City anymore.
 
Furthermore, a different club have now adopted this strategy to great success. Arsenal are currently top of the Premier League and have the second most goals in the competition (45). Amazingly, none of their players have scored more than 8 goals. This is one of the key reasons the Gunners have coped so well with the injury to Gabriel Jesus. He is responsible for just over 11% of their total goal tally. Take him out of the team and Saka, Martinelli, Ødegaard and Nketia are all still there. The graph below illustrates this.
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A telling difference between this graph and the previous one is the proportion of goals which fall into the ‘other’ category. These are goals scored by the remainder of the squad who aren’t their top 4 goal scorers. None of Arsenal’s top scorers have even half the goal tally of the rest of the squad (18). Whereas Haaland has significantly outscored the goal tally of the rest of Man City’s squad.  
 
What’s more is that Arsenal’s group orientated approach to goal scoring provides the team with multiple outlets when playing. Whereas at Man City every player that isn’t Erling Haaland seems to have one job, assist Erling Haaland. The halfway mark in this Premier League season seems to demonstrate that you don’t necessarily need to have the best players to be top of the league. All you need is for your team to be greater than the sum of its parts.

ESEA Keynote Speaker 1 - Professor Jane Ruseski

30/1/2023

 
By Robbie Butler
 
The 14th European Sport Economics Association (ESEA) Conference will be held at University College Cork, Ireland from the 23rd to the 25th of August 2023.

We are delighted to announce the event will include a keynote address by Professor Jane Ruseski (John Chambers College of Business and Economics) of West Virginia University. 

Professor Ruseski is an economist of international standing and will be the first female keynote speaker at the conference. 

Aside for sports economics, Prof. Ruseski has research interests in health economics, health financing and policy,  and industrial organization. She has published in a list of prestigious international peer-reviewed academic journals including Contemporary Economic Policy, Health Economics, Journal of Behavioral and Experimental Economics, Southern Economic Journal, BE Journal of Economic Analysis & Policy, and Journal of Sports Economics. She is a co-editor of Contemporary Economic Policy and an associate editor of the International Journal of Sport Finance.

Those wishing to attend the conference should know that submissions are welcome relating to any area of sports economics including theoretical, empirical and conceptual papers. Please submit an extended abstract including introduction, theoretical background, methods and major finding via the submission portal that can be found on the conference website: www.cubsucc.com/esea-call-for-papers.

Abstract submission deadline: 31st March 2023.
Notification of acceptance: 30th April 2023

Full information about Cork 2023 can be found on the event website: www.cubsucc.com/esea-home/

Call for Papers - 14th European Sport Economics Association (ESEA) Conference

20/12/2022

 
The 14th European Sport Economics Association (ESEA) Conference will be held at University College Cork, Ireland from the 23rd to the 25th of August 2023.

The ESEA Conference is the annual gathering of the European Sport Economics Association. This is a scientific association founded in 2010 that pursues the goal of promoting communications between scientists and practitioners working in the field of sports economics.

The conference is a three-day event hosted by the Centre for Sports Economics and Law (CSEL) at UCC and will take place on the main campus. Prior to the event, a PhD student workshop will take place from the 21st of August to the morning of the 23rd. This will be delivered by international scholars in sports economics. The Conference Gala Dinner will be held on the Thursday evening, 24th August.

Submissions are welcome relating to any area of sports economics including theoretical, empirical and conceptual papers. Please submit an extended abstract including introduction, theoretical background, methods and major finding via the submission portal that can be found on the conference website: www.cubsucc.com/esea-call-for-papers.

Abstract submission deadline: 31st March 2023.
Notification of acceptance: 30th April 2023

Full information about Cork 2023 can be found on the event website: www.cubsucc.com/esea-home/

If you have any questions in relation to the conference, please feel free to contact a member of the local organising committee.

Local Organising Committee: Dr David Butler (CSEL, UCC), Dr Robert Butler (CSEL, UCC), Pat Massey (Compecon)

Christmas Break

19/12/2022

 
Our blog will now take its customary Christmas break and return on Monday the 30th of January 2023.

We would like to wish all our readers a very Happy Christmas and best wishes for 2023.

Free shot conversion rates in hurling

14/12/2022

 
By John Considine
A couple of months ago I was in communication with colleagues about the changing stance of an inter-county free-taker.  The player has one of the more successful conversion rates in 2022.  The communication quickly turned to the difficult in making comparisons with limited amounts of data.  It can be difficult to account for all the possible explanations for variations in outcomes (and that is without dealing with the fact that the players themselves change).  Bigger data may not solve the problem and there can be value in "small" data.  Consider the following picture of the conversion rate for frees (penalised fouls) in the 34 games of the 2022 championship.
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The standout observation is that the lowest conversion rates came on All-Ireland quarter-final day.  Two games on the same day, at the same venue, separated by a couple of hours.  The weather conditions were not perfect but they were not bad.  It is hard to imagine the weather conditions explaining the low conversion rates.

The weather conditions differed dramatically for the games represented by the black bars.  In both cases Limerick and Clare were the teams.  An added complication was the fact that the venue was difference.

I don't have detailed weather data but we can look at the conversion rates by venue and match day.  First, let us look at the conversion rates by venue.  Cusack Park, Ennis is the leftmost venue.
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The 2022 championship was played over 17 different dates.  Matchday 17 is the day of the All-Ireland final.  Matchday 14 is the day of the quarter-finals.  The semi-finals were played on the same weekend but on separate days.
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This brings us back to the players themselves.  Consider the difficulty in comparing them.  How many shots did they take?  From what location on the field did they strike the free?  What were the weather conditions?  What was the venue?  What was the stage of the competition?  Below is a picture that only adjusts partly for the number of shots taken.  It is for all players who struck more than 10 frees that crossed the opponents endline directly for either a score or a wide.
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The four players listed can claim to have the highest conversion rate depending on the cut-off for minimum number.  Alan Murphy nailed 100% of his 10 frees.  If one use a minimum of 20 then it is Noel McGrath.  If one used a minimum of 25 it is Arron Gillane.  Above 30 attempts, it is TJ Reid.
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