There is also the velocity of money, which people tend to forget. MV = PQ is a tautology that tends to be fairly useless in understanding inflation because ther

There is also the velocity of money, which people tend to forget. MV = PQ is a tautology that tends to be fairly useless in understanding inflation because there's no variable there that is reasonably constant. So other approaches fare better, such as looking at the sources of inflation, e.g. imports, relative labor bargaining power, and aggregate demand vs. supply.