On the importance of fixed effects over a short period of time when using sports data: a lesson from home advantage in alpine skiing

Research question: The aim of this paper is to compare the effect of competing in a home country between a racer fixed effects model, which assumes a constant ability over the span of a racer’s career, and a racer per season fixed effects model, which has a more plausible assumption that ability may vary between the seasons. Research methods: We use data on all 50,046 performances among men and 44,311 performances among women from all the top competitions in alpine skiing that took place in the seasons from 2001–2002 to 2017–2018. We use fixed effects estimations in which we compare the performance of racers when they compete in their home country to performance of the same racers when they compete abroad. Results and findings: When using the racer fixed effects model, we find no relationship between competing at home and the likelihood of failing to finish the first run for both genders. However, when using the racer per season fixed effects model, we find that racers have a significantly higher probability of failing to complete the first run when competing abroad. In addition, we find that competing at home has a positive effect on racers’ performance in terms of World Cup points. Implications: Given the widespread use of fixed effects models in sports-related studies, as well as in other fields, this paper illustrates the sensitivity of results to the length of the fixed effects. This should help practitioners and scholars to better understand the underlying assumptions that relate to athletes’ abilities over time.