When the Amazon star ratings drop for a product, it compares less favorably to other products on the search page, and it’s generally understood that will have some negative sales impact. A deep analysis across tens of thousands of products shows how these dynamics manifest longer-term and need to be factored into Amazon business planning on the part of brands.

The Research

Momentum Commerce analyzed a set of over 50,000 products with Amazon star ratings ranging from 5.0 to 4.0 on July 1, 2021. Each of these products also held an Amazon Best Seller badge within a specific subcategory. We then measured what percentage of products at each star rating band retained their badge over the following 12 months.

The Story

When it comes to Amazon star ratings, the analysis shows that the likelihood of a given product maintaining its Best Seller badge drops with every 0.1 decrease in star rating. The biggest impact appears at the 4.2 threshold, most likely due to this being the point the stars visible next to the listing round to 4 as opposed to 4.5.

This dynamic relates to the concept of Durable Dominance on Amazon. When measured against direct competitors on the search page (rather than across a larger category), certain characteristics have a relationship to whether a given product is more or less likely to retain its BSR over time. The most important of these metrics are:

• Relative review count (i.e. how many more/less reviews does a product have versus its average competition on the search page)
• Relative price (i.e. how much more/less does a product cost versus its average competition on the search page)
• Amazon star rating
• Share of Voice

More broadly, brands should understand that a top BSR is remarkably difficult for a single product to hold over time. Even for products with higher star ratings, roughly half of them had lost their Best Seller badge within a matter of months.

Biggest Takeaways for Brands

• Be aware of how changes to digital shelf metrics like star ratings, relative price, or relative review counts will impact downstream sales metrics – and have the capabilities in place to monitor those changes and adjust forecasts accordingly
  • Brands should be realistic about how a drop in something like the Amazon star rating impacts business planning. Any price cuts or increased advertising to increase sales in the face of decreasing star ratings will impact margins at a minimum. 
• A product is best positioned to maintain its BSR over time if it compares favorably to its competition on the SERP across review count, price, star ratings, and share of voice – rather than just a single metric
• Amazon is testing ‘review-less’ search pages – so be prepared to look beyond rating or ‘review moats’ as the sole means of differentiation. Review counts and ratings will remain important, but improving relative price and share of voice need to be part of your strategy
• Outside of reducing the price, when looking to increase the sell-through of a product cost effectively, be less concerned with reducing ACOS and more focused on maintaining a consistent TACOS as ad budgets drop