Don’t trust those Amazon star ratings

The ratings on global shopping websites may mislead buyers with improper data, according to the University of Colorado. A team of researchers proved that the stars you see near the product description on sites like Amazon may not portray the true quality of the product.

The results of the research that involved over 1,300 products and 300,000 ratings showed that the number of stars often didn’t show the real value of things for sale. Users tend to give higher marks to the products that are more expensive, even though many of them may have been objectively evaluated as poor.

The research mostly included technological products, like car batteries and home appliances. The ratings found on the websites mostly didn’t correlate with the results of the professional evaluation. The US magazine that publishes the results of their own testing done in a laboratory, Consumer Reports, was used as the main source of professional ratings.

The study found that, half the time, Amazon reviews and Consumer Reports ratings disagreed about which item in a random pair was better.

“For two randomly chosen products, there is only a 57 per cent chance that the product with the higher average user rating is rated higher by Consumer Reports,” the research said.

The study also found that customers gave a better score to a more expensive product or premium brand than a cheaper alternative even when they had the same Consumer Reports score.

“The combined influence of price and brand image on the average rating is much larger than the effect of objective quality, as measured by Consumer Reports, explaining more than four times as much variance,” the research, published in the Journal of Consumer Research, said.

The paper, called Navigating by the Stars, also discovered that Amazon ratings failed to predict accurately resale values on second-hand market places such as eBay, which is considered another indicator of quality. In contrast, quality scores from Consumer Reports did predict resale value.

The study found that shoppers relied heavily on star ratings when making purchasing decisions, even when the product had a statistically insignificant number of reviews. It said: “Consumers fail to moderate their reliance on the average user rating when sample size is insufficient. Averages based on small samples are treated the same as averages based on large samples.”

Bart de Langhe, assistant professor of marketing at the University of Colorado, said that consumers took star ratings far more seriously than they merited. “You should rely much less on reviews than you currently do,” he told The New York Times.

Julie Law, spokeswoman for Amazon, said: “Amazon customer reviews reflect the feedback, tastes and concerns of real customers, not professional reviewers. That’s what makes them powerful.” She added that the online retailer was now giving more weight to the most recent helpful reviews from purchases that were verified.

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