Concordance or conflict? A 40-year longitudinal study of a South African wine club versus expert ratings and price

Abstract

Purpose This paper aims to investigate the relationship between expert and consumer wine ratings and their association with wine prices. Using a unique longitudinal data set of an informal wine club, it explores whether these two forms of evaluation align or diverge and how each group perceived wine quality via price premiums. Design/methodology/approach The analysis, spanning 1987–2024, is based on 693 paired ratings from two distinct sources: expert evaluations as published in Platter’s South African Wine Guide, and consumer evaluations from an informal but experienced private South African wine club. Agreement between these two rating sources is tested using Cohen’s weighted kappa statistic. A Bayesian regression model is used to assess how each rating source relates to real (consumer price index-deflated) retail wine prices. Findings Although the expert and wine club scores show very low agreement, both independently predict wine prices. Expert ratings have a stronger effect, but consumer ratings also show significant predictive power. This relationship hold across both red and white wines. Practical implications Wine producers and marketers can benefit from displaying both expert and consumer scores, as each appeals to different segments of the market. The data set also underscores the value of long-term consumer panels in understanding price sensitivity. Originality/value This study presents a novel data set that enables the examination of nearly four decades of matched expert and enthusiast wine evaluations in South Africa. It demonstrates how different evaluative perspectives coexist in shaping price premiums, even in the face of diverging views on quality.