Do standard consumer price indexes overstate inflation?
Core argument: Available evidence suggests the CPI-U and the retroactive series using current methods overstate inflation by about 0.70 percentage points per year, while the chained indexes are upwardly biased by roughly 0.40 points per year.
The available evidence suggests that the contemporary CPI-U and R-CPI-U-RS [Consumer Price Index retroactive series using current methods] overstate inflation by around 0.70 percentage points per year, while the chained indexes are upwardly biased by roughly 0.40 points per year. I turn to the creation of a new, more accurate price index for assessing long-term trends in income, earnings, poverty, and wealth. My goal is to use the best estimates of year-to-year changes in prices to the extent I can, but to adjust the estimates from different periods in accord with the research on known biases affecting different indexes at different times. My correction amounts to 1.12 points per year relative to the CPI-U from 1978 to 2000. For 2000-2023 I begin with the published 2023 value and then reduce the year-to-year changes by 0.41 percentage points. This adjustment accounts for bias due to upper-level substitution, new products, quality change, and new outlets. Compared with the published CPI-U, my correction from 2000 to 2023 is 0.68 points per year.


