Another small study done by Joy Hawkins says that the recency of reviews does impact the rankings of those local business listings in Google Search and Google Maps. Like the previous studies, this was not really statistically significant but it is nice to see a case study looking at these in isolation.
One of her clients paused asking for reviews and noticed that their local rankings started to go down. So they had the client ask for reviews again, thus getting more recent reviews and with that, rankings in the Google local results, began to pick up. Joy showed the progress in rankings with this graph:
She said "I have also seen this pattern with other clients of ours. We recently had a client who got filtered back in the summer for keywords they had historically ranked very well for. When I dug into possible reasons why I noticed he hadn’t had a new review in over 3 years. While these are obviously just 2 examples, I have seen this same pattern over and over."
Her previous study said 10 reviews get you a boost and keywords in reviews don't matter.
Forum discussion at Twitter.