Efficient (adj): Policy A is more efficient than policy B if policy A achieves the same result as policy B using fewer resources (i.e. same result; lower cost).
Example: From the UK Telegraph:
Contraception is almost five times cheaper as a means of preventing climate change than conventional green technologies, according to research by the London School of Economics.
Every £4 spent on family planning over the next four decades would reduce global CO2 emissions by more than a ton, whereas a minimum of £19 would have to be spent on low-carbon technologies to achieve the same result, the research says.
The report, Fewer Emitter, Lower Emissions, Less Cost, concludes that family planning should be seen as one of the primary methods of emissions reduction. The UN estimates that 40 per cent of all pregnancies worldwide are unintended.
Phew (wiping forehead in the universal sign of relief), I made it through without an inappropriate and/or immature joke.
