Buying online? You might get low-quality item even if it's highly reviewed

Do you always go for a highly reviewed product while shopping online? If yes, chances of you buying a low-quality item are also high, not less, researchers have warned.

The findings, published in the journal Psychological Science, indicate that people tend to favour a product that has more reviews, even when it has the same low rating as an alternative product.

"It's extremely common for websites and apps to display the average score of a product along with the number of reviews. Our research suggests that, in some cases, people might take this information and make systematically bad decisions with it," said lead author on the study Derek Powell of Stanford University in California.

By examining a large dataset of reviews from Amazon.com, the researchers were able to build a statistical model of how people should choose products.

"We found that faced with a choice between two low-scoring products, one with many reviews and one with few, the statistics say we should actually go for the product with few reviews since there's more of a chance it's not really so bad.

"But participants in our studies did just the opposite: They went for the more popular product, despite the fact that they should've been even more certain it was of low quality," Powell explained.

The researchers wanted to examine how people weigh information about other people's decisions.

Looking at actual products available on Amazon.com, Powell and colleagues, found no relationship between the number of reviews a product had and its average rating.

In other words, real-world data show that a large number of reviews is not a reliable indicator of a product's quality.

With this in mind, the researchers wanted to see how people would actually use review and rating information when choosing a product.

In one online experiment, 132 adult participants looked at a series of phone cases, presented in pairs.

The participants saw an average user rating and a total number of reviews for each phone case and indicated which case in each pair they would buy.

Across various combinations of average rating and number of reviews, participants routinely chose the option with more reviews.

This bias was so strong that they often favoured the more-reviewed phone case even when both of the options had low ratings, effectively choosing the product that was, in statistical terms, more likely to be low quality.

A second online experiment that followed the same design and procedure produced similar results.

The researchers found that this pattern of results fit closely with a statistical model based on social inference.

That is, people seem to use the number of reviews as shorthand for a product's popularity, independent of the product's average rating.