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What Is the Chained Consumer Price Index (CPI)?


The Chained Consumer Price Index (CPI), or Chained CPI, can provide a more refined approach to measuring inflation than the standard CPI. It does so by incorporating consumer behavior and the substitutions they make when prices change. This is a valuable tool to help determine policy adjustments and it can also help you understand how inflation could impact your finances and future financial planning.

A financial advisor can take inflation and policy adjustments into account when helping you put together a financial plan.

What Is the Chained CPI?

The Chained CPI is a variation of the traditional Consumer Price Index that’s designed to provide a more accurate measure of changes in the cost of living. Unlike the standard Consumer Price Index, which uses a fixed basket of goods and services, the Chained CPI accounts for changes in consumer behavior as they make substitutions when prices change. This provides a more realistic picture of inflation and cost of living adjustments over time.

The federal government uses the Chained CPI to adjust income tax brackets, social security benefits and other government programs to reflect inflation. It’s preferred over the traditional CPI for these applications because it can reflect with greater accuracy the reality of how economic changes impact consumers. Financial advisors often consider the Chained CPI when advising clients on retirement planning, as it can influence projected cost of living adjustments and long-term financial strategies.

How the Chained CPI Is Calculated

The Chained CPI’s formula accounts for consumers’ substitutions pertaining to the goods and services they purchase. This calculation incorporates data collected from consumer spending patterns and price changes over two consecutive periods to create a chain of indexes. By continuously updating the goods and services used in this calculation, the Chained CPI reduces upward bias in inflation measurement, making it a more dynamic and accurate indicator.

Data Collection and Analysis

A woman reviews her budget as inflation rises.

The Chained CPI starts with collecting data on consumer spending habits and price changes. The Bureau of Labor Statistics (BLS) gathers detailed information on what consumers buy, how much they pay, and how their purchasing patterns shift over time. This data is collected monthly through surveys and price sampling across various regions and stores.

Chain Linking Formula

The Chained CPI is calculated using a chain linking formula that involves two steps:

  1. Price relatives calculation: The BLS first calculates price relatives for each item. Price relatives are the ratios of the current period prices to the previous period prices.
  2. Expenditure share adjustment: Next, the BLS adjusts these price relatives based on changes in expenditure shares. If the price of one item rises significantly, consumers may buy less of it and more of a cheaper substitute. The Chained CPI captures this shift by adjusting the expenditure weights.

These steps are repeated for each pair of consecutive periods, creating a chain of linked indexes. This chain linking process allows the index to continuously update and reflect changes in consumer behavior.

Frequently Asked Questions About the Chained CPI

What Is the Chained CPI?

The Chained Consumer Price Index (CPI) is an inflation measure that accounts for changes in consumer behavior, such as substituting cheaper alternatives when prices rise. This approach provides a more accurate reflection of the cost of living over time compared to the traditional CPI.

How Does the Chained CPI Differ From the Traditional CPI?

The traditional CPI uses a fixed basket of goods and services, not accounting for consumer substitution when prices change. In contrast, the Chained CPI updates the basket to reflect current consumer behavior, typically resulting in lower inflation estimates.

How Is the Chained CPI Calculated?

The Chained CPI uses a chain-weighted formula, which averages data from consecutive periods to account for fluctuations in consumer choices. This methodology adjusts the basket of goods and services regularly to reflect current consumer spending patterns.

Why Is the Chained CPI Considered More Accurate?

By accounting for consumer substitution between goods and services when prices change, the Chained CPI reduces the upward bias present in the traditional Consumer Price Index. This leads to a more realistic measure of inflation and cost-of-living adjustments.

How Does the Chained CPI Impact Social Security and Taxes?

The federal government uses the Chained CPI to adjust tax brackets, social security benefits, and other programs for inflation. Because the Chained CPI generally reports lower inflation rates, adjustments based on it tend to be smaller, potentially leading to slower growth in benefits and tax thresholds.

What Are the Criticisms of the Chained CPI?

Critics argue that the Chained CPI may understate inflation for certain groups, such as the elderly, who have less flexibility in changing their spending patterns. Additionally, lower inflation adjustments can result in slower increases in social security benefits and other inflation-indexed payments.

Bottom Line

A woman reviews the latest data on the Chained CPI.

The Chained CPI incorporates consumers’ behavior as they make substitutions when prices rise, which is considered a more comprehensive measure of inflation. It can reflect with greater accuracy the true cost of living, making it a valuable tool for economic analysis and policy adjustments. While it often reports lower inflation rates when compared with the traditional CPI, it can help align adjustments in tax brackets, Social security benefits and other government programs with real-world economic conditions.

Inflation Tips

  • If you want a financial plan that takes into account the changes in cost of living, a financial advisor can help. Finding a financial advisor doesn’t have to be hard. SmartAsset’s free tool matches you with up to three vetted financial advisors who serve your area, and you can have free introductory calls with your advisor matches to decide which one you feel is right for you. If you’re ready to find an advisor who can help you achieve your financial goals, get started now.
  • The last thing you want to risk is running out of money in retirement, so it’s important to make sure your retirement plan takes into account inflation and the future cost of living.

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