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Chain-Weighted CPI

Chain-Weighted CPI

What Is Chain-Weighted CPI?

Chain-weighted CPI, or chained CPI, is an alternative measurement for the Consumer Price Index (CPI) that considers changes to consumer spending patterns to give a more accurate picture of the cost of living in view of the goods that consumers actually buy.

Understanding Chain-Weighted CPI

Chain-weighted CPI for every month accounts for changes in consumer preference and product substitutions due to changes in relative prices of goods made by consumers. Subsequently, this measurement is viewed as a more accurate gauge of cost of living than the traditional fixed-weighted CPI. This is essentially because it adjusts in light of the mix of goods that consumers actually buy as opposed to focusing on a fixed basket of goods. Then again these adjustments likewise make the chain-weighted CPI a less timely indicator and a less accurate measure of inflation.

The U.S. Bureau of Labor Statistics publishes the chain-weighted CPI for every month alongside its other regular reports on prices and inflation. CPI-U, otherwise called regular of headline CPI, and other comparative indexes are calculated by gathering the month to month prices of a basket of consumer goods that is held relatively steady in its organization and weighting from one month to another, with updates just like clockwork. Conversely, the month to month basket of consumer goods whose prices are used to calculate chained CPI is likewise updated month to month to mirror the mix of goods that consumers actually bought in that month.

These adjustments are intended to account for two things that a fixed-basket CPI would disregard.

  1. First, over time, both consumer preferences for goods change and the type and quality of goods accessible usually improves as technology advances. By adding new introduced goods and adjusting the weighting of existing goods to better guide the patterns of consumer spending on various types of goods, the chained CPI can capture these effects.
  2. Second, consumers will generally adjust their buying behavior inside and across various categories of goods in light of relative price changes among these goods. For instance, when the price of ground meat relative to chicken rises, consumers are probably going to buy more chicken and less hamburger. This is known as the substitution effect. Because consumers substitute, the actual cost of their total purchases, will quite often be more stable than a price index of a fixed basket of goods with fixed weight would infer.

As per BLS, these adjustments makes chain-weighted CPI a nearer estimate to a cost-of-living index than other CPI measures.

Notwithstanding, this improvement in measuring the actual costs of consumers' spending decisions introduces several limitations. BLS points out that, because making these adjustments takes additional time and depends on estimates of consumer behavior that must be updated and overhauled later, chain-weighted CPI is a much less timely indicator that regular CPI. Month to month chain-weighted CPI numbers are updated and reconsidered retroactively every month, with a last index number just a brief time sometime later. This can make it less useful as a real-time indicator of the cost-of-living. Regular CPI is viewed as the last estimate for every month that it is published.

Furthermore, though chained CPI might be a better indicator of the cost of living, these equivalent adjustments likewise make it a more unfortunate indicator of inflation. Inflation is the decline in the purchasing power of a monetary unit over time, which is a distinct concept from the cost of living. Changing the structure and weighting of the basket of goods used to measure a price index to reflect actual changes in consumer behavior undermines the index's usefulness for measuring the decline in purchasing power because many changes to consumer purchasing choices may in whole or in part act naturally driven by changes in purchasing power or consumer expectations thereof. Notwithstanding this, chain-weighted CPI is often professed to be a measure of inflation.

At long last, the total effect of chain-weighted CPI adjustments is that it will in general be more stable and show a more slow rate of increase in the cost of living (or as it is considered normal misconstrued, the rate of inflation) over time compared to regular CPI. This might be viewed as a feature or a drawback of chain-weighted CPI relying upon the interests and incentives of the person reporting and using the index. In particular, according to the government's point of view, using chain-weighted CPI as opposed to regular CPI to make cost of living adjustments to public benefits payments and marginal tax rate brackets results, separately, in lower payments to beneficiaries and higher effective tax rates as tax payers incomes will creep in to higher tax brackets quicker than upward adjustments to the brackets will be made.

Chain-Weighted CPI Example

Think about the impact of two comparative and substitutable products — meat and chicken — in the shopping basket of Mrs. Smith, a common consumer. Mrs. Smith buys two pounds of meat at $2/lb. what's more, two pounds of chicken at $1/lb. After a year, the price of meat has risen to $6/lb. while the price of chicken has risen to $2/lb. While the two prices have risen, the price of meat relative to the price of chicken is higher (hamburger is currently three times the cost of chicken instead of two times).

Mrs. Smith, hence, adjusts her spending pattern because of the higher price of hamburger and buys three pounds of chicken but just a single pound of meat to cushion the impact that the rise in prices will have on her household budget.

Chain-Weighted CPI and Taxation

A US federal law passed in 2017 applied the chain-weighted CPI rather than primary CPI for adjusting the incremental increases in income tax brackets. By switching to this measurement, the increases on tax bracket adjustments will be similarly more modest every year. This transition to chain-weighted CPI is expected to push more residents into higher tax brackets over time, subsequently expanding the taxes they owe and, thus, expanding the tax revenue collected by the Internal Revenue Service (IRS).

The year-over-year change will probably be a percentage point or less over a given year, but there is a massive difference over time. For instance, between January 2000 and April 2021, primary CPI increased by 57.6 percent, but chain-weighted CPI just increased by 49.6 percent.

For taxpayers with raises indexed to primary CPI, this change may eventually result in them paying more tax in a higher bracket regardless of not feeling essentially more well off. As inflation accelerates this effect will turn out to be more pronounced, implying that more taxpayers will start feeling the nibble of higher taxes as well as paying something else for the goods and services they buy.


  • Chain-weighted CPI can capture both general changes in spending, as consumer preferences change, and substitution effects, when relative prices change.
  • In 2017, chain-weighted CPI was substituted for regular CPI in setting federal income tax brackets.
  • Chain-weighted CPI considers real-word purchasing choices to give a more accurate picture of the cost of living.
  • The adjustments in chain-weighted CPI make it a better measure of the cost of living, but a less accurate measure of inflation.