Hello Roy, do you have any sense of how you could quantify the value of Product Reviews in Google shopping? For example, take a look at the screenshot below for a search on 'Powder Skis'.
Product reviews are a massive confidence factor for shoppers. You could very easily measure the value of product reviews on your own site by doing a sitewide A/B test where you hide them (if you have them currently), and compare the Conversion Rates. You could then infer from that the potential difference in value to push them in your feed.
Another way you could do that kind of test is to push product reviews for only half of your catalog. For this type of testing, I've often used odd/even product IDs, to avoid biasing the test and control groups. You can then compare those two product sets for differences in Click Through Rates (CTR) and Conversion Rates. You'd want to account for differences in their performance leading up to the test, but with the odd/even method, you're only going to really need to adjust for a few huge moving skus, and the rest should balance out pretty well.
If you haven't collected product reviews yet, and are trying to determine whether it's a worthwhile project, it's difficult to forecast how big of a lift they'd provide, but I can say with certainty that they affect both CTRs and Conversion Rates in every test I've run. However, since they were so conclusive, I haven't had reason to run a similar test in the past couple of years--it's "standard practice" to me at this point, based on the results I've generally seen.
Besides, product reviews aren't just for shoppers. I've used them to drive category sort logic, identify good opportunities for promotions, and to put pressure on suppliers during negotiations. They're an incredible resource to the business, if you look for ways to use the data, not just display it.
Thanks for the question Russell. Drop me a line if you have any other questions. I love to talk shop.
Up and to the right,