Ditty,
Article quality is inherently subjective in the hard-AI sense. A panel of
judges will consider accurate articles full of spelling, grammar, and
formatting errors superior in quality to hoax, biased, spam, or out-of-date
articles with perfect grammar, impeccable spelling, and immaculate
formatting.
In my studies of the short popular vital articles (WP:SPVA) the closest
correlation with subjective mean opinion score quality I've found so far is
sentence length. But it has diminishing returns and the raw correlation is
+0.2 at best.
The entirely subjective nature of article quality is additional support for
automating accuracy review.
Best regards,
James