What they did
Backlinko checked whether the exact search keyword appeared in each ranking page's title tag and set that against ranking position across the 11.8 million results.
What they found
There was essentially zero correlation between an exact-match keyword in the title and a higher position. The study reported the same flat, near-zero relationship for page loading speed.
How much weight to give it
A weak correlation cuts both ways. It does not mean titles are worthless, only that a crude exact-match test across every query type finds no pattern. Google reads meaning, not just literal strings, so semantic relevance in a title can matter even when the exact keyword does not.
What it doesn't prove
Absence of a correlation in one blunt measure is not evidence of no effect. The check ignored partial matches, word order and intent, all of which could carry real signal.