El ColegiadoData on refereeing in the Liga

Study

VAR in the Liga

Did the arrival of VAR change how Liga referees whistle?

  • 2014-18 vs 2018-22
  • 9,880 matches
  • Updated on 3 October 2026
  • Method

Key takeaways

  1. Penalties / match: 0.290 → 0.364 (+26%) between 2014-18 and 2018-22, p = 0.001. See
  2. Reds / match: 0.243 → 0.216 (−11%) between 2014-18 and 2018-22, p = 0.14. See
  3. Yellows / match: 5.14 → 4.98 (−3%) between 2014-18 and 2018-22, p = 0.05. See
  4. Fouls / match: 27.8 → 26.9 (−3%) between 2014-18 and 2018-22, p = 0.001. See
  5. VAR arrives in 2018-19, the same season the payments end. See

Penalties / match

2014-18

0.290

2018-22

0.364

+26% · p (permutation) = 0.001

Reds / match

2014-18

0.243

2018-22

0.216

−11% · p (permutation) = 0.14

Yellows / match

2014-18

5.14

2018-22

4.98

−3% · p (permutation) = 0.05

Fouls / match

2014-18

27.8

2018-22

26.9

−3% · p (permutation) = 0.001

Main limitation: VAR arrives the same season the payments end (2018-19): this study cannot separate the two effects. All limitations

Penalties / match, whole Liga

By season; the dotted line marks the arrival of VAR

VAR

Reds / match, whole Liga

By season; the dotted line marks the arrival of VAR

VAR

Yellows / match, whole Liga

By season; the dotted line marks the arrival of VAR

VAR

Fouls / match, whole Liga

By season; the dotted line marks the arrival of VAR

VAR

Limitations

  • VAR arrives the same season the payments end (2018-19): this study cannot separate the two effects.
  • 2019-20 and 2020-21 seasons: matches behind closed doors, which may also change behaviour.
  • Comparison of whole-Liga averages, four seasons before against four seasons after; p computed by permuting the seasons.
  • Fouls are only available from 2005-06.

Definitions

Expected points
Before each match, the bookmakers' odds give the probability of a win, a draw and a defeat. Expected points = 3 × P(win) + P(draw). A positive deviation means the club took more points than the market predicted. Because the team's strength is already built into the odds, a big club has no "automatic" positive deviation.
q-value
With hundreds of comparisons, some look extreme by chance. The Benjamini-Hochberg correction accounts for this: a deviation is only called notable if q < 0.05. Otherwise: inconclusive. Inconclusive does not mean "no effect": with 11 matches, only a deviation of about ±1.57 points per match could have been detected.
Difference-in-differences
We measure the club's change between two periods, then subtract the change of a comparison group over the same periods. What remains is the change specific to the club.
Strength-adjusted measures
Each match is compared with Liga matches from the same season, at the same venue type (home/away) and between teams of comparable strength according to the odds. A positive value is favourable to the club.

Details in the methodology →