I'm not worried about what he did in the past or bending the curve or other sort of, you know, marginal things.

WHITEHOUSE: Press Briefing

They all face roughly the same (world) demand curve, but each country will have a different marginal cost for getting the oil out.

FORBES: The Global Oil Addiction: An Interactive Graphic

The Laffer Curve-effect is more likely to work miracles if the highest marginal income tax rate is very high to begin with say over 50 or 60 percent and if the taxpayer has control of when to realize income for tax purposes.

FORBES: The Real Problem With Obama's Tax-Cut Priorities