where M represents the money supply, r the nominal interest rate (the refinancing rate), Y the
level of real output (GDP), and ξt denotes the error term.
Coefficients on the money supply and the interest rate should capture the effects of monetary
policy on inflation. Economic theory would suggest that money supply growth, foreign price
inflation and nominal exchange rate depreciation would have a positive effect on domestic
inflation, while increases in the interest rate and higher output growth (to the extent that it
reflects higher productive capacity and not excess demand) would have a negative effect on
domestic inflation.
We go on to estimate Equation (6), measured in terms of percentage changes of the variables
from the previous year, except for the interest rate, where the end-of-period nominal
(refinancing) rate is used.