Request for Comments" on quality for Wikidata. It is an attempt to describe quality in a top down approach. It is about words, it is abstract and well, I wish them well.
Wikidata has qualities. When you understand Wikidata by what it is and what it does you understand the not so abstract qualities it has. Its principle aim is to bring structure to the data that is in the Wikimedia projects.
The first quality that Wikidata brought was that it replaced the text based interwiki links. The improvement was important; in a short space of time the quality of these interwiki links improved and the associated number of edits went down. The quality of the interwiki links is not absolute but there has been no research on the follow up.
Interwiki links represent connection between articles of Wikimedia projects that are about the same subject. Within a Wikipedia, a Wikisource there are links that are in essence similar to Wikidata statements. When a university is mentioned, the subject may be a student or staff at that university and when the statement has been made there is a reason for inclusion in categories. We can research the concurrence of such statements and Wikilinks. Quality improves when the concurrence improves.
When enough data is available, it becomes possible to use Wikidata statements in templates. Templates and info boxes expect high quality data in Wikidata and the available data is typically not good enough. When it is easy to make statements to wiki links and red links, the data in an info box will grow with the added statements.
We do need to work on the quality for our readers. This is done best by leveraging the data we have and engage our communities not only to link articles together but also by expanding these links with the statements that bind them together.
Yes, we will have to solve abstract issues but the reality is that they are not so abstract. Issues have their basis in what it is we have to understand this in what we hope to achieve; serving the world with the sum of all our available knowledge.