An operational definition matters most because it lets other researchers:

1. A finding is only useful if someone else can check it. 2. Checking it means measuring the same thing the same way. 3. An operational definition is a precise description of our variables. 4. It is important in allowing others to understand exactly how and what a researcher measures in a particular experiment. 5. Nothing about it removes the need for analysis, participants or review. _Source: OpenStax Psychology 2e (CC BY 4.0), Ch 2 'Psychological Research', sections 2.1-2.4_