Amazon Reviews are Just as Reliable as Book Critics (A Study)

Harvard Business School have conducted a study into the reviews posted on Bookseller Amazon, compared to newspaper or “Traditional” reviews.

They studied the Top 100 Non-Fiction titles between 2004 and 2007.

To review the information, they used the review aggregator, which provides summaries of professional reviews, from 40 media outlets such as The Guardian, New York Times and The Washington Post. They also compared these to Amazon reviews of the same books.

The findings indicated that while both had their issues, there was no overall quality differences in the reviews.

This could be a big boost to Indie Authors, who do not usually have the advantage of “Traditional” reviews.

The Findings

Debut Authors

Amazon are more likely to give debut authors a good review. They pointed out this could mean Amazon reviewers are more likely to discover new books, and that “traditional” reviewers may be slower to discover new books from unknown authors.

“Traditional” reviews are more likely to focus on works of already established authors, authors who have a large media presence or have previously won awards.

If the author has a link to the reviewer organisation, this will increase the likelihood of reviews by 25%, and that review, in 5% of cases, was found to be more favourable.

It did however point out that the likelihood of review occurred because it was felt that the author would appeal to its readership, rather than out and out collusion.


Firstly it pointed out that there was “virtually no quality assurance” in Amazon reviews. Amazon reviews can be “fixed”, with false reviews being posted by “unknown” sources, such as the author, publisher or friends of the author.

That said the overall review did not statistically differ from “Traditional” reviews, so while they may be a hint of bias, the rest of the reviewing public make up for that and give an honest review.


The study was limited in only using Non Fiction Titles. While in theory it should have no basis for fiction, it does show that Amazon can be a reliable source for reviews.

For Indie authors who do not/ can not get a traditional review, it gives the confidence that if they get reviewed positively, it is genuine.

Consumers can relax and shop with confidence, that the review has validity.

I am not going to conduct an in-depth opinion of the study, as I think it stands by itself.


Study Abstract

PDF of The Research Paper

News article


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