Unanswered Questions Tag Counts

Question

By clicking on the Unanswered button from the homepage, a list of tags appears on the right side, with what I am guessing is the number of unanswered questions next to it.

When I click one of those tags, I get a list of unanswered questions with that tag. All is well. A new list of tags appears on the right, presumably a list of tags related to the tag I've clicked on.

There are some tags that appear here, that also appeared on the original unanswered page. There is a substantial difference in the count next to the tags on this page than the original page. I assume it's counting the number of questions that have been tagged with the current tag as well as the second tag. However when I click it, the number of results climbs by a number that is not what was listed by the tag - often close but sometimes off by thousands.

The answer on the following meta question, seems to only apply to all questions, not unanswered questions. when I attempt it on unanswered questions, I get a blank page:

Narrow search by tag

If I visit: https://stackoverflow.com/questions/tagged/php+html and click the Unanswered tab, I get what I'm expecting - questions with both tags and no answers.

If I visit https://stackoverflow.com/unanswered/tagged/php+html, I get a list of questions with one or the other tag, and often have (not-upvoted) answers.

My question is: what are those counts by those tags in the unanswered section actually counting?

I have read this: The Unanswered Section vs. the Unanswered Question Tab: A Critique but it relates to the answers on the unanswered questions. My concern is primarily with the tag search.

Answer 1

I'm not sure it was the same when you asked this question, but as for the number of results now the explanation looks simple.

The tags "facets" should simply be counting the occurrences of other tags in the questions which your search return. The tagged->unanswered search is doing an AND between tags; unanswered->tagged is doing an OR.

This is demonstrated by the fact that in one I only see questions with both tags you chose, while in the other I see questions which only have either and clicking more tags from the selector increases results most of the time.