There are several ways to add Schema aggregate rating markup, but before we discuss the “How”, let’s review what a Schema aggregate rating value actually is. ;-)
The Schema.org website defines the Schema aggregateRating property value as:
The overall rating, based on a collection of reviews or ratings, of the item.
Two things to keep in mind about this:
- That an aggregate rating value is calculated from several customer ratings / reviews for the current webpage content — WooCommerce product reviews, for example.
- Google prefers, and often double-checks, that Schema markup reflects the current content of the webpage. So, if you want to manually set aggregate rating and/or review values in your Schema markup, make sure that these customer ratings and reviews also appear in your webpage content (ie. that these ratings and reviews are visible).