The takeaway
Most economic time series reflect what we know today. That is, they provide the most current, most accurate versions of the data. But what if we want to look back at what we thought was true yesterday? That’s where ALFRED can help.
FRED’s archival data service has turned 20
ALFRED, launched in 2006, has helped many researchers better understand economic history by taking them back in time to see the data that were available on specific dates. ALFRED illuminates windows in time to help you accomplish many tasks:
- Identify and correct data errors. The January 6, 2021, release of the Economic Policy Uncertainty Index contained a 300% spike—an error that was corrected the next day.
- Compare different methods to collect data. In November 2021, Realtor.com changed how it reported the number of houses for sale. This change could impact the analysis of trends and cycles.
- Track periodic comprehensive updates. Major economic indicators such as real GDP undergo periodic comprehensive updates to reflect best measurement practices. Between 1991 and 2023 there were eight updates, each adjusting reference years for inflation.
- Improve data accuracy and completeness. Data collection is complex. Reporting timely data creates a tradeoff between accuracy and speed. Employment figures undergo two regular types of revisions: twice when additional information from employers becomes available and two additional annual benchmarking revisions to realign those data with state administrative records. These revisions make the data more accurate.
An example of data revisions captured in ALFRED
Our ALFRED graph above shows how a natural disaster resulted in large data revisions. Hurricane Harvey first made landfall on Friday, August 25, 2017, near Rockport, Texas. Hurricane Irma hit the lower Florida Keys on Sunday, September 10. A total of 87 counties, representing 7.7% of national employment, were declared federal disaster areas. Although data collection wasn’t severely disrupted, a steep decline in food services and drinking places and below-trend growth in some industries likely reflected the impact of both hurricanes.
The first release of employment data for September 2017 (blue bar) showed a decrease in employment of 33,000 persons. The second (red bar) and third (green bar) releases showed increases in employment of as many as 38,000 persons. Keeping track of data vintages is important for storytelling and analysis.
To learn more about putting ALFRED to good use, see this essay.
How this graph was created: Search ALFRED for and select “All Employees: Total Nonfarm, Monthly, Seasonally Adjusted.” Click on “Edit Graph” and select the “Edit Bars” tab. For Bar 1, change the “As-of date” to “2017-10-06.” For Bar 2, change the “As-of date” to “2017-11-03.” Adjust the date range to “2017-01-01” to “2017-11-01.” Click “Edit Graph” and change the “Units” to “Change from Year Ago, Thousands of Persons” and click “Copy to all.”
Suggested by Diego Mendez-Carbajo.