Answers are grounded in this paper and cite their sources.
While readability formulas were intended as a quick benchmark for indexing readabilty, they are inherently unreliable: they depend on criterion (calibration) passages too short to reflect cohesiveness, too varied to support between-formula comparisons, and too text-oriented to account for the effects of lists, enumerated sequences,and tables on text comprehension. But readability formulas did spark decades of research on what comprehension really involoves.
No takes yet. Share an insight, caveat, or question.
Karen A. Schriver (2000) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: