Caveats and pitfalls in crowdsourcing research: the case of soccer referee bias

Caveats and pitfalls in crowdsourcing research: the case of soccer referee bias In a recent crowdsourcing project, 29 teams analyzed the same data set to address the following question: “Are football (soccer) referees more likely to give red cards to players with dark skin tone than to players with light skin tone?” The major finding was that the results of the individual teams varied widely, from no effect to highly significant correlations between skin color and the rate of red cards, which some teams interpreted as indicative of a referee bias. We analyzed the same data using a Poisson log-linear regression model and obtained an odds ratio of 1.34 (95%-CI, 1.13–1.59), which means that players with a darker skin tone have in fact a slightly higher odds of receiving a red card. This result is in agreement with the median odds ratio of 1.31 from all 29 teams. We then extended the original study by investigating the likelihood of receiving yellow cards. If a referee bias was in fact present, it would be plausible to see a similar association. However, players with darker skin tone were significantly less likely to receive a yellow card, with an odds ratio of 0.94 (95%-CI, 0.91–0.97). The risk of receiving a card is most strongly affected by a player’s position, and there are significantly more players with darker skin tone at center back and defensive midfield where receiving red cards is generally more likely. Taken together, our results do not support the hypothesis of a referee bias. Our most important finding, however, is that the perceived diversity of results from the crowdsourcing teams is due to placing too much emphasis on dichotomous decisions (significant vs. nonsignificant). When we focus on point estimates and their reasonable bounds, the individual substudies predominantly reinforce each other. We argue that data scientists should put less emphasis on statistical significance and instead focus more on the careful interpretation of confidence intervals or alternative methods for measuring the effect size and its precision. International Journal of Data Science and Analytics Springer Journals

Caveats and pitfalls in crowdsourcing research: the case of soccer referee bias

Loading next page...
Springer International Publishing
Copyright © 2017 by Springer International Publishing Switzerland
Computer Science; Data Mining and Knowledge Discovery; Database Management; Artificial Intelligence (incl. Robotics); Computational Biology/Bioinformatics; Business Information Systems
Publisher site
See Article on Publisher Site


You’re reading a free preview. Subscribe to read the entire article.

DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 12 million articles from more than
10,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Unlimited reading

Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.

Stay up to date

Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.

Organize your research

It’s easy to organize your research with our built-in tools.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

Monthly Plan

  • Read unlimited articles
  • Personalized recommendations
  • No expiration
  • Print 20 pages per month
  • 20% off on PDF purchases
  • Organize your research
  • Get updates on your journals and topic searches


Start Free Trial

14-day Free Trial

Best Deal — 39% off

Annual Plan

  • All the features of the Professional Plan, but for 39% off!
  • Billed annually
  • No expiration
  • For the normal price of 10 articles elsewhere, you get one full year of unlimited access to articles.



billed annually
Start Free Trial

14-day Free Trial