How is the consumer price index used

how is the consumer price index used

Consumer Price Index

October 1st, 2004


A Series Authored by Walter J. "John" Williams

"The Consumer Price Index" (Part Four in a Series of Five)

October 1, 2006 Update

(September 22, 2004 Original)

This installment has been updated from the original 2004 version to incorporate additional research on earlier changes to the CPI. The source for most of the information in this installment is the Bureau of Labor Statistics, which generally has been very open about its methodologies and changes to same. The BLS Web site: contains descriptions of the CPI and its related methodologies. Other sources include my own analyses of the CPI data and methodological changes over the last 30 years as well as interviews with individuals involved in inflation reporting.


Payments to Social Security Recipients Should be Double Current Levels

Inflation, as reported by the Consumer Price Index (CPI) is understated by roughly 7% per year. This is due to recent redefinitions of the series as well as to flawed methodologies, particularly adjustments to price measures for quality changes. The concentration of this installment on the quality of government economic reports will be first on CPI series redefinition and the damages done to those dependent on accurate cost-of-living estimates, and on pending further redefinition and economic damage.

The CPI was designed to help businesses, individuals and the government adjust their financial planning and considerations for the impact of inflation. The CPI worked reasonably well for those purposes into the early-1980s. In recent decades, however, the reporting system increasingly succumbed to pressures from miscreant politicians, who were and are intent upon stealing income from social security recipients, without ever taking the issue of reduced entitlement payments before the public or Congress for approval.

In particular, changes made in CPI methodology during the Clinton Administration understated inflation significantly, and, through a cumulative effect with earlier changes that began in the late-Carter and early Reagan Administrations have reduced current social security payments by roughly half from where they would have been otherwise. That means Social Security checks today would be about double had the various changes not been made. In like manner, anyone involved in commerce, who relies on receiving payments adjusted for the CPI, has been similarly damaged. On the other side, if you are making payments based on the CPI (i.e. the federal government), you are making out like a bandit.

In the original version of this background article, I noted that Social Security payments should be 43% higher, but that was back in September 2004 and only adjusted for CPI changes that took place after 1993. The current estimate adjusts for methodology gimmicks introduced since 1980.

Elements of the Consumer Price Index (CPI) had their roots in the mid-1880s, when the Bureau of Labor, later known as the Bureau of Labor Statistics (BLS), was asked by Congress to measure the impact of new tariffs on prices. It was another three decades, however, before price indices would be combined into something resembling today’s CPI, a measure used then for setting wage increases for World War I shipbuilders. Although published regularly since 1921, the CPI did not come into broad acceptance and use until after World War II, when it was included in auto union contracts as a cost-of-living adjustment for wages.

The CPI found its way not only into other union agreements, but also into most commercial contracts that required consideration of cost/price changes or inflation. The CPI also was used to adjust Social Security payments annually for changes in the cost of living, and therein lay the eventual downfall to the credibility of CPI reporting.

Let Them Eat Hamburger

In the early 1990s, press reports began surfacing as to how the CPI really was significantly overstating inflation. If only the CPI inflation rate could be reduced, it was argued, then entitlements, such as social security, would not increase as much each year, and that would help to bring the budget deficit under control. Behind this movement were financial luminaries Michael Boskin, then chief economist to the first Bush Administration, and Alan Greenspan, Chairman of the Board of Governors of the Federal Reserve System.

Although the ensuing political furor killed consideration of Congressionally mandated changes in the CPI, the BLS quietly stepped forward and began changing the system, anyway, early in the Clinton Administration.

Up until the Boskin/Greenspan agendum surfaced, the CPI was measured using the costs of a fixed basket of goods, a fairly simple and straightforward concept. The identical basket of goods would be priced at prevailing market costs for each period, and the period-to-period change in the cost of that market basket represented the rate of inflation in terms of maintaining a constant standard of living.

The Boskin/Greenspan argument was that when steak got too expensive, the consumer would substitute hamburger for the steak, and that the inflation measure should reflect the costs tied to buying hamburger versus steak, instead of steak versus steak. Of course, replacing hamburger for steak in the calculations would reduce the inflation rate, but it represented the rate of inflation in terms of maintaining a declining standard of living. Cost of living was being replaced by the cost of survival. The old system told you how much you had to increase your income in order to keep buying steak. The new system promised you hamburger, and then dog food, perhaps, after that.

The Boskin/Greenspan concept violated the intent and common usage of the inflation index. The CPI was considered sacrosanct within the Department of Labor, given the number of contractual relationships that were anchored to it. The CPI was one number that never was to be revised, given its widespread usage.

Shortly after Clinton took control of the

White House, however, attitudes changed. The BLS initially did not institute a new CPI measurement using a variable-basket of goods that allowed substitution of hamburger for steak, but rather tried to approximate the effect by changing the weighting of goods in the CPI fixed basket. Over a period of several years, straight arithmetic weighting of the CPI components was shifted to a geometric weighting. The Boskin/Greenspan benefit of a geometric weighting was that it automatically gave a lower weighting to CPI components that were rising in price, and a higher weighting to those items dropping in price.

Once the system had been shifted fully to geometric weighting, the net effect was to reduce reported CPI on an annual, or year-over-year basis, by 2.7% from what it would have been based on the traditional weighting methodology. The results have been dramatic. The compounding effect since the early-1990s has reduced annual cost of living adjustments in social security by more than a third.

The BLS publishes estimates of the effects of major methodological changes over time on the reported inflation rate (see the "Reporting Focus" section of the October 2005 Shadow Government Statistics newsletter — available to the public in the Archives of Changes estimated by the BLS show roughly a 4% understatement in current annual CPI inflation versus what would have been reported using the original methodology. Adding the roughly 3% lost to geometric weighting — most of which not included in the BLS estimates — takes the current total CPI understatement to roughly 7%.

There now are three major CPI measures published by the BLS, CPI for All Urban Consumers (CPI-U), CPI for Urban Wage Earners and Clerical Workers (CPI-W) and the Chained CPI-U (C-CPI-U). The CPI-U is the popularly followed inflation measure reported in the financial media. It was introduced in 1978 as a more-broadly-based version of the then existing CPI, which was renamed CPI-W. The CPI-W is used in calculating Social Security benefits. These two series tend to move together and are based on frequent price sampling, which is supposed to yield something close to an average monthly price measure by component.

The C-CPI-U was introduced during the second Bush Administration as an alternate CPI measure. Unlike the theoretical approximation of geometric weighting to a variable, substitution-prone market basket, the C-CPI-U is a direct measure of the substitution effect. The difference in reporting is that August 2006 year-to-year inflation rates for the CPI-U and the C-CPI-U were 3.8% and 3.4%, respectively. Hence current inflation still has a 0.4% notch to be taken out of it through methodological manipulation. The C-CPI-U would not have been introduced unless there were plans to replace the current series, eventually.

Traditional inflation rates can be estimated by adding 7.0% to the CPI-U annual growth rate (3.8% +7.0% = 10.8% as of August 2006) or by adding 7.4% to the C-CPI-U rate (3.4% + 7.4% = 10.8% as of August 2006). Graphs of alternate CPI measures can be found as follows. The CPI adjusted solely for the impact of the shift to geometric weighting is shown in the graph on the home page of The CPI adjusted for both the geometric weighting and earlier methodological changes is shown on the Alternate Data page, which is available as a tab at the top of the home page.

Hedonic Thrills of Using Federally Mandated Gasoline Additives

Aside from the changed weighting, the average person also tends to sense higher inflation than is reported by the BLS, because of hedonics, as in hedonism. Hedonics adjusts the prices of goods for the increased pleasure the consumer derives from them. That new washing machine you bought did not cost you 20% more than it would have cost you last year, because you got an offsetting 20% increase in the pleasure you derive from pushing its new electronic control buttons instead of turning that old noisy dial, according to the BLS.

When gasoline rises 10 cents per gallon because of a federally mandated gasoline additive, the increased gasoline cost does not contribute to inflation. Instead, the 10 cents is eliminated from the CPI because of the offsetting hedonic thrills the consumer gets from breathing cleaner air. The same principle applies to federally mandated safety features in automobiles. I have not attempted to quantify the effects of questionable quality adjustments to the CPI, but they are substantial.

Then there is "intervention analysis" in the seasonal adjustment process, when a commodity, like gasoline, goes through violent price swings. Intervention analysis is done to tone down the volatility. As a result, somehow, rising gasoline prices never seem to get fully reflected in the CPI, but the declining prices sure do.

How Can So Many Financial Pundits Live Without Consuming Food and Energy?

The Pollyannas on Wall Street like to play games with the CPI, too. The concept of looking at the "core" rate of inflation-net of food and energy-was developed as a way of removing short-term (as in a month or two) volatility from inflation when energy and/or food prices turned volatile. Since food and energy account for about 23% of consumer spending (as weighted in the CPI), however, related inflation cannot be ignored for long. Nonetheless, it is common to hear financial pundits cite annual "core" inflation as a way of showing how contained inflation is. Such comments are moronic and such commentators are due the appropriate respect.

Too-Low Inflation Reporting Yields Too-High GDP Growth

As is discussed in the final installment on GDP, part of the problem with GDP reporting is the way inflation is handled. Although the CPI is not used in the GDP calculation, there are relationships with the price deflators used in converting GDP data and growth to inflation-adjusted numbers. The more inflation is understated, the higher the inflation-adjusted rate of GDP growth that gets reported.


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