Methodology · sensitivity analysis
The Reality Index headline rate uses BLS CES Relative Importance weights for apples-to-apples comparison with CPI. But other defensible weighting schemes produce different — and generally larger — gaps. This page shows what the Reality Index headline looks like under five different methodological choices.
Why this page exists. Critics will argue that any single inflation index has cherry-picked its methodology. Our defense is to show what happens to the headline rate under alternative defensible methodologies and let readers see for themselves that the gap between Reality Index and official CPI persists across the range. The default headline (32% cumulative gap) is the conservative anchor. Alternative defensible weightings produce gaps ranging from 29% to 61% over the same 45-year window.
The principle. We do not switch to whichever scenario produces the largest gap. We use the default — BLS's own household-spending weights — because it is the methodologically cleanest comparison to official CPI. The sensitivity analysis exists to show the range, not to pick the highest number.
Headline gap range, 1980 → 2025
Across five defensible methodology choices, the Reality Index gap over CPI ranges from +29.3% (raw CES Aggregate Shares) to +60.6% (BEA PCE weights, used by the Federal Reserve for monetary policy). The default headline of +32.0% is on the conservative end of the range.
The same underlying bucket inflation indexes — what families paid for housing, food, healthcare, transportation, and so on — produce a wide range of headline rates depending on how the categories are weighted. This is true of every inflation index, including CPI itself. CPI's headline number is fundamentally a weighting decision applied to thousands of underlying price observations. Change the weights, change the headline.
Reality Index uses BLS's own household-spending weights as default because that methodology choice is the hardest to attack: critics cannot argue we cherry-picked the basket when the weights come from BLS's empirical Consumer Expenditure Survey. The methodological gap we are flagging is in the price measurement, not the weighting.
The alternative weighting scenarios on this page exist to address the legitimate question: what if BLS's CES weights themselves understate certain categories? The National Academies Panel on Redesigning the BLS Consumer Expenditure Surveys has explicitly stated that underreporting in CES "appears to differ sharply across commodities, raising the possibility of differential biases in the Consumer Price Index." This is not a fringe critique. It is a mainstream methodological concern documented by BLS's own academic advisory body.
The BEA PCE scenario is particularly worth understanding. PCE weights are what the Federal Reserve actually uses for monetary policy decisions. PCE weights healthcare differently than CPI does (PCE includes employer-paid premiums in the healthcare bucket, which CPI does not, because CPI is supposed to capture out-of-pocket consumer prices). When you apply the Fed's own preferred weighting scheme to our retail price data, the cumulative gap balloons to 61%. The Fed's own weighting methodology, applied to real retail prices, produces an inflation rate nearly twice what the Fed reports.
The takeaway
The 32% cumulative gap between Reality Index and official CPI is the conservative answer. It uses the most defensible weighting scheme (BLS CES Relative Importance, the same weights BLS uses for CPI itself) and the most independent price data available (KFF, NCES, FHFA, EIA, AAA, BLS Average Price Data).
Other defensible methodologies produce gaps ranging from 29% to 61%. The gap exists under every one. What changes is the magnitude. What does not change is the direction: under every reasonable methodology, the goods and services families actually buy have inflated faster than the official Consumer Price Index reports.
That is the finding. The methodology choices that follow from it — which gauge the Federal Reserve should use, how COLA adjustments should be computed, what the right reference rate is for contracts and pensions — are policy debates Reality Index does not attempt to resolve. We just publish the range honestly.