A/B test proves reviews drive up to 14.2% conversion increase
Monday, 24 August 2009

espares Ratings & ReviewseSpares is the UK’s largest spare parts retailer, specializing in accessories and consumables for electric home appliances. They offer more than 400,000 different products from over 500 manufacturers. They recently ran an A/B test to conclusively prove whether reviews increase conversion on their Web site.

A/B test solidly proves impact

While other testing methodologies can suggest a strong correlation between an increase in conversion and the addition of Ratings & Reviews, A/B tests more conclusively prove results. An A/B test looks at increases in conversion rates on the same products during the same time-frame, which effectively eliminates all other factors, such as product popularity or seasonality, to conclusively represent correlations.

How they did it

To exclude possible biases, eSpares randomly selected three products within their extensive product catalog with a significant amount of reviews and similar ratings. Then, for five months, they randomly served site visitors either product information that contained review content or product information without review content. The test was run until there was a statistically accurate sample size for
all products, and no promotions were run during testing period.

For each product, eSpares measured the relative increase in conversion rates for the visitors who were served Ratings & Reviews content versus those who were not. They then tested to see how confident they were that the results were not due to chance.

Reviews drive up to 14.2% increase in conversion

eSpares reports that each product experienced between a 6.3% and 14.2% increase in conversion for visitors served Ratings & Reviews content. This means that visitors who viewed product information containing review content converted from visitors to buyers between 6.3% and 14.2% more often than persons who did not receive copy containing reviews.

For their two products with relative increases in conversion of 6.3% and 6.6%, eSpares is 80% confident that the increases did not occur due to chance. For their product with the largest relative conversion increase (14.2%), they are more than 95% confident.

The bottom line

Once again, customer reviews are shown to drive sales conversion. In this case, eSpares found that, when everything else was controlled, visitors viewing the same products with Ratings & Reviews converted between 6.3% and 14.2% more often.

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