Crowdsourcing the assessment of wine quality : Vivino ratings, professional critics, and the weather

Crowdsourcing platforms - such as Vivino - that aggregate the opinions of large numbers of amateur wine reviewers represent a new source of information on the wine market. We assess the validity of aggregated Vivino ratings based on two criteria: correlation with professional critics' ratings and sensitivity to weather conditions affecting the quality of grapes. We construct a large, novel dataset consisting of Vivino ratings for a portfolio of red wines from Bordeaux, review scores from professional critics, and weather data from a local weather station. Vivino ratings correlate substantially with those of professional critics, but these correlations are smaller than those among professional critics. This difference can be partly attributed to differences in scope: Whereas amateurs focus on immediate pleasure, professionals gauge the wine's potential once it has matured. Moreover, both crowdsourced and professional ratings respond to weather conditions in line with what viticulture literature has identified as ideal, but also hint to detrimental effects of global warming on wine quality. In sum, our results demonstrate that crowdsourced ratings are a valid source of information and can generate valuable insights for both consumers and producers.