Hyphens, En Dashes, Em Dashes

Q. Please settle an internal argument. Which punctuation is correct for the following title: “Transitioning to More-Rigorous Assessments” or “Transitioning to More Rigorous Assessments”?

A. Please see CMOS 7.89, section 2, under “adverb not ending in ly + participle or adjective” for a similar example (“most-skilled” versus “most skilled”). The hyphen affects the meaning, so you must choose accordingly. “More-Rigorous” refers to the quality of the assessments; “More Rigorous” could mean the same thing, or it could refer to a larger quantity of rigorous assessments. As always, rewording is better than relying on punctuation. “Making Assessments More Rigorous” and “Using Rigorous Assessments More Frequently” are clear.