Consumers are increasingly asking: Is this a need or a want? A discernible gap between the rate of price increases for necessities and the one for discretionary purchases is putting the Federal Reserve’s tightening path at risk of veering off course.

Making matters more difficult, the Fed’s preferred inflation gauge does a pitiful job of capturing the quandary facing many households that live paycheck to paycheck. The so-called core PCE is the central bank's go-to inflation metric. It is derived by netting out the necessities of food and energy from personal consumption expenditures. But the core PCE also minimizes the weight of rent and over-emphasizes health care due to Medicaid and Medicare’s inputs.

Classify the following items within the core PCE as necessities and then track them as an aggregate using what we can call the Household Budget Inflation Gauge. Included are food and nonalcoholic beverages, fuels, clothing, housing, utilities, health care, health insurance, homeowners’ insurance, auto insurance, higher education and the phone, utility and internet bills. As of the latest reading, these costs are rising at a 2 percent rate compared with last year.