The Atlanta Fed's macroblog provides commentary on economic topics including monetary policy, macroeconomic developments, financial issues and Southeast regional trends.
- BLS Handbook of Methods
- Bureau of Economic Analysis
- Bureau of Labor Statistics
- Congressional Budget Office
- Economic Data - FRED® II, St. Louis Fed
- Office of Management and Budget
- Statistics: Releases and Historical Data, Board of Governors
- U.S. Census Bureau Economic Programs
- White House Economic Statistics Briefing Room
April 14, 2006
Why We Focus On Core Inflation
Identifying changes in the inflation trend is generally only possible after long periods of time have passed. Moreover, methods to measure the underlying inflation pattern in the data, such as long-run averages, can reveal a shift in the inflation trend only well after that change has occurred.
To improve the inflation signal in the price data, economists have often appealed to so-called core inflation measures, like the CPI excluding food and energy items—goods notorious for causing transitory fluctuations in the aggregate price data. A more recent approach is the use of trimmed-mean estimates that systematically strip out the more extreme—and presumably most transitory—price changes. These measures have been shown to substantially reduce short-run variation in the inflation estimates and, hopefully, give policymakers a quicker read on shifts in the inflation trend. Indeed, these estimates have predicted the long-term growth rate of the CPI better than either the CPI or the more traditional CPI excluding food and energy. For example, since 1990, monthly changes in the median CPI and the 16% trimmed-mean CPI have been about twice as effective as changes in the overall CPI for predicting the longer-term CPI inflation trend (that is, the 36-month annualized percent change).
The following picture is meant to illustrate the superiority of core measures of inflation in predicting headline inflation over a 3-year horizon:
The way to read this graph is as follows: The points corresponding to the number 1 on the horizontal axis answer the question "What is the root-mean-squared error of a prediction of inflation over the next 36 months, where those predictions are based on one month's observations on the CPI itself (the red line), the CPI excluding food and energy components (the blue line), the median CPI (the yellow line), and a core measure with the most extreme 16% of prices stripped out (the purple line)?" (If you are not familiar with statistics, the lower the root mean-squared error, the better the prediction.) The points associated with the number 2 on the horizontal axis correspond to the question "which measure is a better predictor of longer-run inflation if we use 2 months of data?" The points corresponding to the number 3 answer the question "which measure is a better predictor of longer-run inflation if we use 3 months of data", and so on.
If what we are interested in is getting an accurate guess about what inflation is going to be over the next several years, then this exercise indicates that (a) it is better to focus on inflation over the past 9-12 months than to extrapolate on the basis of just one or two months; and (b) it is better to focus on core inflation than headline inflation.
Something to keep in mind when the March CPI numbers roll out next Wednesday.
TrackBack URL for this entry:
Listed below are links to blogs that reference Why We Focus On Core Inflation:
- A Closer Look at Changes in the Labor Market
- Should We Be Concerned about Declines in Labor Force Growth?
- Labor Report Silver Lining? ZPOP Ratio Continued to Rise in September
- The ZPOP Ratio: A Simple Take on a Complicated Labor Market
- What Do U.S. Businesses Know that New Zealand Businesses Don't? A Lot (Apparently).
- 5-Year Deflation Probability Moves Off Zero
- Should I Stay or Should I Go Now?
- No Wage Change?
- Getting to the Core of Goods and Services Prices
- Different Strokes for Different Folks
- November 2015
- October 2015
- September 2015
- August 2015
- July 2015
- June 2015
- May 2015
- April 2015
- March 2015
- February 2015
- Business Cycles
- Business Inflation Expectations
- Capital and Investment
- Capital Markets
- Data Releases
- Economic conditions
- Economic Growth and Development
- Exchange Rates and the Dollar
- Fed Funds Futures
- Federal Debt and Deficits
- Federal Reserve and Monetary Policy
- Financial System
- Fiscal Policy
- Health Care
- Inflation Expectations
- Interest Rates
- Labor Markets
- Latin America/South America
- Monetary Policy
- Money Markets
- Real Estate
- Saving, Capital, and Investment
- Small Business
- Social Security
- This, That, and the Other
- Trade Deficit
- Wage Growth