VAR reduces effective play time in Portugal's top football league

A study by researcher Luís Filipe Santos, supervised by Professor Bruno Damásio at Nova IMS, examined 1,616 matches from Portugal's Primeira Liga (Liga Betclic) and the second division between the 2015/16 and 2018/19 seasons. Using a Difference‑in‑Differences econometric approach, the analysis compared the two seasons before VAR’s introduction (2015/16‑2016/17) with the two seasons after it was adopted (2017/18‑2018/19). The findings show that the proportion of effective playing time fell from 52.77 % (47 min 30 s) to 51.46 % (46 min 19 s), a reduction of roughly one to two minutes per match. This loss persisted across the post‑VAR periods, while the second‑division control league, which only introduced VAR in 2023/24, showed stable values. Professor Damásio explained the method: “O que nós fizemos foi reconstruir uma Primeira Liga, digamos, fictícia, que é a Primeira Liga na ausência de vídeoárbitro…”. The study suggests that the VAR system has a measurable, lasting impact on the flow of games in Portugal’s top tier.