Who is the author of AggregatedRating in Schema.org definition?

Question

Who is the author of AggregatedRating if the ratings are added by me, but they actually come from Google and Apple and maybe some other places?

The documentation does not give any explanation.

So if I added the JSON-LD there, am I the author? It comes from the app store so is the author the app store(s)? Or is the author all the individuals who gave their rating?

Because author is actually a required field or at least Google's testing tool gives an error "A value for the author field is required." because I left it empty for now.

JSON-LD:

{
  "@context": "https://schema.org",
  "@graph": [
    {
        "@type": "UserReview",
        "name": "App store reviews",
        "itemReviewed": {
            "@type": "Thing",
            "@id": "https://habinator.com",
            "name": "Habinator App"
        },
        "datePublished": "2019-08-01",
        "reviewRating": {
            "@type": "AggregateRating",
            "ratingValue": "4.9",
            "ratingCount": "27",
            "bestRating": "5",
            "worstRating": "1"
        }
    }
  ]
}

Answer 1

Individual reviews require an author, who is the person who wrote the reviews. AggregatedRating does not.

Answer 2

The error in the SDTT

The property name (author) in the error line is not indented, i.e., not on the same level as the AggregateRating properties like ratingValue, ratingCount etc.

That is a signal that the error is not about your AggregateRating.

You can click the error line to find out which item it belongs to. It will highlight the type of the item in the source code view on the left. In your case, it will highlight the UserReview.

So that means that Google requires (if you want to get the rich result) the UserReview to have an author, not the AggregateRating.

UserReview and AggregateRating

That said, your structured data probably doesn’t convey what you want it to convey. A UserReview is for one review written by one user. The AggregateRating value for the reviewRating property would mean that this user rated the reviewed thing 27 times.

author of AggregateRating

I would say AggregateRating items should typically not get the author property at all. It’s data extracted from authored content, but not authored content itself, which makes it hard to say whether the author would be the one who extracted the data, or whether it would be a list of all users whose rating is part of the aggregate.