By TheStreet Staff What Is the Personal Consumption Expenditures Index (PCE)?What are people spending their hard-earned paychecks on? While prices constantly change, and some may go up while others go down, monitoring personal expenditures is a great way to gauge how prices are trending over time—because when people can afford to buy fewer everyday things, that meansinflation is on the rise. But inflation itself is notoriously hard to measure, which is why economists often look to several consumer and producer price indexes in order to get a complete picture. Each month, the Bureau of Economic…