This factor is the most obvious. The higher your average star rating, the better received you will be by the search engine.
Google's robots read everything. That being said, they do keep in mind how relevant the written reviews are to your business. For example, a review that says "John's plumbing services was awesome!" will be much more helpful than "John was really helpful."
As a general SEO rule of thumb, Google loves seeing a business that is active on the web. Your reviews are no exception to this rule, so you should be trying to get your business reviewed as often as possible by recent customers.
As one would expect, the search engine giant gives a little bit more weight to customer reviews that were posted on its own review page.
Factor number 4 doesn't mean that the search engine totally ignores reviews that are on other review sites, so don't rule sites such as YellowPages, Tripadvisor and Urbanspoon out.
No review site, no matter how small, should be ignored. If you can get reviews pouring in from YellowPages, MojoPages, CitySearch, SuperPages, etc, you will fare a lot better than you otherwise would have.
This is another area in which the search engine giant plays favorites. Getting a high volume of reviews on a prominent review site like some of the ones that we've already mentioned will help you out a lot more than the alternative.
How many reviews do you currently have? It doesn't matter. When factoring who is going to get ranked the highest, Google considers which businesses have the highest volume of current reviews. In short, they want to know that your business is still actively serving customers right now.
Google places is designed to help you attract local attention. In order for them to rank you high on the local results, they want as much evidence as possible that your business is indeed local. As such, it behooves you to try to get customers to mention the city or town that you are in when writing a review. For example, your customers should be writing "Fred's Fitness is the best gym in East Orange, NJ," instead of "Fred's Fitness is the best gym in the area."
Although you cannot control these ranking factors, you can guide them by getting your business established on as many ranking sites as possible and goading customers to write reviews in the first place. To learn more, feel free to contact the Nextiny team!