By specifying a π > 0 {\displaystyle a_{\pi }>0} , the Taylor rule says that an increase in inflation by one percentage point should prompt the central bank to raise the nominal interest rate by more than one percentage point (specifically, by 1 + a π {\displaystyle 1+a_{\pi }} , the sum of the two coefficients on π t {\displaystyle \pi _{t}} in the equation above). Since the real interest rate is (approximately) the nominal interest rate minus inflation, stipulating a π > 0 {\displaystyle a_{\pi }>0} implies that when inflation rises, the real interest rate should be increased. The idea that the real interest rate should be raised "more than one-for-one" to cool the economy when inflation increases (requiring the nominal interest rate to increase more than inflation does) has sometimes been called the Taylor principle.[7]