The U.S. Census Bureau Index of Economic Activity (IDEA) is an aggregation of 15 of the Census Bureau’s primary economic data series that provides a single time series constructed as a weighted average.

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

The U.S. Census Bureau Index of Economic Activity (IDEA) is an aggregation of 15 of the Census Bureau’s primary economic data series that provides a single time series constructed as a weighted combination. 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 and IDEA Working Paper for more information.


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


The IDEA is an aggregation of 15 of the Census Bureau’s primary economic data series that provides a single time series constructed as a weighted average. This monthly index is 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 Inventories
Advance Economic Indicator Report
Retail Trade and Food Services Sales
Advance Monthly Retail Trade
Total Construction Spending
Construction Spending
Wholesale Inventories
Advance Economic Indicator 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.

Three datasets will be updated each business day that will include:

  • Monthly IDEA values available back to August 2004.
  • IDEA input values including published economic data series values.
  • Principal component weights for each of the input economic data series.

All daily vintages of the above datasets will be available for download.

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.

No. The IDEA uses only publicly available data in its construction.

The IDEA is found at the top of the U.S. 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 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 Quarterly Services Survey.

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 20 percent in magnitude. This approximation deteriorates for percentage changes of larger magnitude.

The month-to-month percentage changes for each monthly economic data series included on the IDEA plots 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 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. Recall that the IDEA combines measures from fifteen distinct monthly series into a single (standardized) series with 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), (2) values below ±2 standard deviations and above ±1 standard deviation of the centerline (third lightest shade of blue in Figure 1 below), (3) values below ±3 standard deviations and above ±2 standard deviations of the centerline (second lightest shade of blue in Figure 1 below), and (4) values above ±3 standard deviations of the centerline (lightest shade of blue Figure 1 below).

IDEA data visualization image
Figure 1: IDEA Data Visualization

All processes - including the IDEA - have some form of variation. Regardless of how well a production process operates, there will always be an inherent or natural variability that exists. This natural variability or “background noise” is considered normal while 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 plots outside the control limits (lightest shade of blue);
  • Four out of five consecutive points plot on the same side of the centerline exceed 2 standard deviations (second lightest shade of blue);
  • Two out of three consecutive points that plot on the same side of the centerline exceed 2 standard deviations (third lightest shade of blue);
  • Eight consecutive points plot 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 its long-term mean (computed August 2004 through February 2020).

Because the PCA weights for one or more individual data series can be negative, the sums of the squares of the PCA weights equal 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 history of the Index Value for any particular month, hover over the Index line in the visualization or download the “Index_Values.csv” on the “Downloads” tab.

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