Abstract This study examines how price-matching guarantees (PMGs) influence consumer behaviour in online retail. Using a Difference-in-Differences design (DiD), the paper tracks how product ratings react to within-product price changes during PMG periods. PMGs alone have no effect, but price increases under an active PMG reduce ratings, with impacts intensifying over time and concentrating on cheaper, less visible items. To probe mechanisms, the paper links review texts to the product–platform panel and builds transparent dictionaries for price/value language and sentiment. When prices rise under PMG, references to price/value spike, while placebo topics (quality, service, delivery) remain flat; sentiment shifts little. Event-study tests show flat pre-trends, supporting identification. Overall, PMGs act as market signals whose disciplinary bite emerges when prices move, especially where buyers are highly price sensitive or visibility is low. Antitrust and policy implications include safeguarding pricing transparency and consumer protection while balancing informational benefits against risks of anti-competitive conduct and consumer harm.
Robbiano et al. (Mon,) studied this question.