On Monday, September 16, Google announced[1] that they would be restricting review stars in SERPs to specific schemas and would stop displaying reviews that they deemed to be "self-serving." It wasn't clear at the time when this change would be happening, or if it had already happened.
Across our daily MozCast tracking set, we measured a drop the morning of September 16 (in sync with the announcement) followed by a continued drop the next day ...
The purple bar shows the new "normal" in our data set (so far). This represents a two-day relative drop of nearly 14% (13.8%). It definitely appears that Google dropped review snippets from page-1 SERPs across the roughly 48-hour period around their announcement (note that measurements are only taken once per day, so we can't pinpoint changes beyond 24-hour periods).
Review drops by category
When we broke this two-day drop out into 20 industry categories (roughly corresponding to Google Ads), the results were dramatic. Note that every industry experienced some loss of review snippets. This is not a situation with "winners" and "losers" like an algorithm update. Google's changes only reduced review snippets. Here's the breakdown ...
Percent drops in blue are <10%, purple are 10%-25%, and red represents 25%+ drops. Finance and Real Estate were hit the hardest, both losing almost half of their SERPs with review snippets (-46%). Note that our 10K daily data set broken down 20 ways only has 500 SERPs per category, so the sample size is low, but even at the scale of 500 SERPs, some of these changes are clearly substantial.
Average reviews per SERP
If we look only at the page-1 SERPs that have review snippets, were there any changes in the average number of