A simple rule of thumb holds that, if one knows this quantity, one can (*) divide 72 by its value to calculate the doubling period.
The fact that the short-term form of this quantity cannot fall below zero is known as the ZLB or zero lower bound problem. A linear approximation usually written as i approximately equals r plus pi relates the real and nominal forms of this quantity and is known as the Fisher equation. The LIBOR is an average of several of these quantities that, in another context, can be measured in basis points. A simple rule of thumb holds that, if one knows this quantity, one can (*) divide 72 by its value to calculate the doubling period. Banks with low reserves may apply to the Fed to receive the "discount" form of this quantity, which is charged at the "federal funds" level between banks. For 10 points, name this rate that may be computed in a "simple" or "compound" fashion, which denotes how much a lender charges a borrower.
The fact that the short-term form of this quantity cannot fall below zero is known as the ZLB or zero lower bound problem.
interest rates [prompt on "rate of return" or "return (on investment)" or equivalents if the answerer appears to be a bank or creditor]