There is idea behind that, but continuous is not enough.
The variable is all transfers, taxes and benefits T = [all taxes - all benefits] as function of income per person (including children). T starts negative (benefits are negative taxes).
Goal: monotonously increasing effective marginal T rate.
The productivity paradox (also the Solow computer paradox) is the business process analysis observation that, as more investment is made in information technology, worker productivity may go down instead of up. This observation has been firmly supported with empirical evidence from the 1970s to the early 1990s.
Before investment in IT became widespread, the expected return on investment in terms of productivity was 3-4%. This average rate developed from the mechanization/automation of the farm and factory sectors. With IT though, the normal return on investment was only 1% from the 1970s to the early 1990s.
Always visualize first. Human 'eyballing' is a good pattern detector.
Linear correlation is just one pattern the data can have.
Unfortunately many social science publications have reviewers who know only the basics and can't judge or accept statistically valid analysis that is outside their competence. Fit it into line or nothing.
The variable is all transfers, taxes and benefits T = [all taxes - all benefits] as function of income per person (including children). T starts negative (benefits are negative taxes).
Goal: monotonously increasing effective marginal T rate.