The U.S. Census Bureau Index of Economic Activity (IDEA) is a weighted combination of 15 of the Census Bureau’s primary economic data series, constructing a single time series that reflects their overall movement.

Last Updated 11:30 a.m. November 8th, 2022

The U.S. Census Bureau Index of Economic Activity (IDEA) is a weighted combination of 15 of the Census Bureau’s primary economic data series, constructing a single time series that reflects their overall movement. This monthly index is constructed from time series of actual and estimated monthly growth rates. As the underlying data are subject to revision, the IDEA is calculated daily, incorporating the most recent values, new estimates, and revisions in each component series.


Values for the index are available starting at August 2004 and will be updated on each business day. Historical data of the index are available for download on the “Downloads” tab.


Access the IDEA methodology, IDEA FAQs, and IDEA Working Paper for more information.


Feedback can be shared by email at EID.Economic.Index@census.gov.


The IDEA is a weighted combination of 15 of the Census Bureau’s primary economic data series, constructing a single time series that reflects their overall movement. It is a monthly index, constructed from time series of actual and estimated monthly growth rates of these 15 series.

Series
Source
Business Applications
Business Formation Statistics
Exports of Goods and Services
International Trade: Goods & Services
Housing Units Authorized in Permit-Issuing Places
New Residential Construction
Housing Units Completed
New Residential Construction
Housing Units Started
New Residential Construction
Imports of Goods and Services
International Trade: Goods & Services
Manufacturing Inventories
Manufacturers' Goods
Manufacturing Value of New Orders
Manufacturers' Goods
New Orders for Durable Goods
Advance Report Durable Goods
New Single-Family Houses for Sale
New Residential Sales
New Single-Family Houses Sold
New Residential Sales
Retail Trade and Food Services Sales
Advance Monthly Retail Trade
Retail Inventories
Advance Economic Indicators Report
Total Construction Spending
Construction Spending
Wholesale Trade Inventories
Advance Economic Indicators Report

The IDEA will be updated each business day to ensure it reflects each new and/or updated published value(s) of the input data series. There will be some days where no input series change, and the index value will remain the same as it was on the previous day.

Each business day, two datasets will be updated. All daily vintages of the below datasets will be available for download.

  • Monthly IDEA values back to August 2004.
  • IDEA inputs of published economic data series values.

In addition, the dataset of nowcasted values* for economic data series that were used to compute the index before they were published for the current month will be available for download at the end of the data processing month.

The principal component weights* for each of the input economic data series are updated annually, beginning August 14th, 2024. The dataset of current and historic weights is available for download.

*For more information on principal components and nowcasting, see the IDEA Methodology.

No. The IDEA uses only publicly available data in its construction. See the table in FAQ #2 for the list of included data series.

The IDEA is featured at the top of the Census Bureau Briefing Room webpage, https://www.census.gov/economic-indicators/.

Datasets can be accessed on the "Downloads" tab within the visualization on this webpage.

We continue to explore adding other relevant Census Bureau economic data series to the IDEA in the future. We are also researching how to incorporate other series that are not on a monthly frequency, like the Census Bureau's Quarterly Services Survey (QSS).

With respect to the IDEA, the term “growth rate” refers to the log(current month value) – log(prior month value). 100 times the growth rate is approximately equal to the month-to-month percentage change when the latter is less than 10 percent in magnitude. This approximation deteriorates for percentage changes of much larger magnitude.

The month-to-month percentage changes for each monthly economic data series included in the IDEA visualization match the values provided by each economic data product in the Briefing Room (https://www.census.gov/economic-indicators/).

Yes, all input data series are seasonally adjusted. Read more about Census Bureau seasonal adjustment at https://www.census.gov/topics/research/seasonal-adjustment.html.

The IDEA time series is presented in a process control chart. Control charts are useful because they help distinguish between variation that is inherent in a process and is therefore expected versus variation that is unusual and, in many cases, unexpected. The IDEA combines measures from fifteen distinct monthly time series into a single series that is then standardized to have a mean of zero and a standard deviation of 1. Consequently, the centerline of the control chart is at zero. The chart highlights four distinct regions: (1) values falling within ±1 standard deviation of the centerline (darkest shade of blue in Figure 1 below), (2) values between ±2 standard deviations and ±1 standard deviation of the centerline (third lightest shade of blue in Figure 1), (3) values between ±3 standard deviations and ±2 standard deviations of the centerline (second lightest shade of blue in Figure 1), and (4) values outside ±3 standard deviations of the centerline (lightest shade of blue in Figure 1).

Depiction of the IDEA time series from August 1, 2014 to December 1, 2022.
Figure 1: IDEA Data Visualization

All processes – including the IDEA – have some form of variation. Regardless of how well a production process operates, it will always have an inherent or natural variability. This natural variability or “background noise” is considered normal when the data points fall within determined limits or do not exhibit a trend. In the framework of statistical quality control, this variability is often referred to as “a stable system of chance causes.” A process that is operating with only chance causes of variation present is said to be in statistical control.

Few processes remain stable forever. The IDEA process could, for example, be affected by an economy-wide event, or one of the component series might be affected by a major weather event. Sources of variability that are not part of the chance causes of variation are called “assignable causes” or “special causes.”

In monitoring the IDEA control chart, we recommend considering the following indicators to assess stability (Tague 2004) using the bands in various shades of blue as a guide:

  • A single point that is outside the control limits (lightest shade of blue);
  • Two out of three consecutive points on the same side of the centerline and exceeding 2 standard deviations (second lightest shade of blue);
  • Four out of five consecutive points on the same side of the centerline and exceeding 1 standard deviation (third lightest shade of blue);
  • Eight consecutive points that are on the same side of the centerline (in any of the blue bands);
  • An obvious consistent, nonrandom pattern (e.g., an upward or downward monotone trend).

Tague, N.R. (2004). The Quality Toolbox (2nd Edition). ASQ Quality Press.

A zero value of the IDEA indicates that the current value is not different from IDEA’s long-term mean (computed using the index values from August 2004 through the most recent May, but excluding the values from March 2020 through August 2020).

As is standard for principal components analysis, the PCA weights are scaled so the sums of the squares of the PCA weights equals 1.

The Main screen highlights changes to the Current Month’s index value. At the start of a new data month, there will be no previous value as it is the first day the Current Month is available. To see the history of the Index Value for any particular month, hover over the Index line in the visualization or download the annual “Index_Values.csv” files on the “Downloads” tab.

Yes, there have been two methodology updates. Additional details on these updates are included in the IDEA Methodology.

  • Effective August 14th, 2024, the span to compute the PCA weights was updated. Originally, the weights were computed using data from August 2004 through February 2020. The updated span is August 2004 through the latest May, excluding March 2020 through August 2020.

    The same span is used as the time frame for fitting the time series model used for nowcasting. The PCA weights and model fitting will now be updated once a year using data for the updated span. See the “Weights.csv” file on the “Downloads” tab for historic PCA weight values. Vintages of the daily IDEA values before and after this update can be viewed in the annual “Index_Values.csv” files, also available on the “Downloads” tab.

    This update uses more recent data in the PCA analysis, while ensuring stable weights through the year so changes in the Index values are driven by changes in the indicator input series.

  • Effective July 10th, 2025, the nowcasting model was updated. To improve the nowcasts of the exports and imports of goods and services time series, which are typically the last of the 15 index inputs to be released each month, we modified the nowcasting model to include advance estimates of exports and imports of goods released in the Advance Economic Indicators Report. Along with being available earlier, these advance trade estimates differ from the final trade estimates used in the index in that they cover only exports and imports of goods, whereas the final trade estimates cover exports and imports of both goods and services. With the overlap between the two sets of trade estimates, however, adding the advance trade estimates to the nowcasting model (though not to the index itself) substantially improves the nowcasts of the final trade estimates which are used in the index.


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