sliding scale

sliding scale (plural sliding scales)

1. A pricing scheme for a product or service where a price range is set and the customer is charged based on where their financial resources fall within the range.
2. A slide rule.
3. A continuous set of measurement values for which the item being measured can change its value easily.
   • 2020 August 7, Jonathan Liew, “Phil Foden stars to offer Manchester City glimpse of multiple futures”, in The Guardian‎:

     not in his favoured midfield role, either but as a false No 9: the sort of role Guardiola only hands to his chosen, crystalline few: Mario Götze at Bayern Munich (less successfully), Lionel Messi at Barcelona (a little more so). Where Foden eventually ends up on that sliding scale is a game of pointless conjecture. But it speaks volumes of Foden’s versatility, technical ability, effortless aggression and tireless running that Guardiola felt that this was the time to find out.