CES Birth/Death Model Frequently Asked Questions
- Do the birth/death factors vary from first preliminary to final estimate?
No, the birth/death factor for a given month does not change between first preliminary, second preliminary, and final sample-based estimates. However, the birth/death factors used in the reestimated values from April of the benchmark year to December of
the benchmark year are updated during the benchmarking process to reflect newly forecasted birth/death values.
- Are birth/death factors seasonally adjusted?
No, they are calculated using population data that is not seasonally adjusted, and the factors are applied to the sample-based not seasonally adjusted estimates. Months with generally strong seasonal increases such as April, May, and June generally have
a relatively large positive factor. Conversely, months with overall strong seasonal decreases, such as January, generally have a relatively large negative factor.
- Can I subtract the birth/death adjustment from the seasonally adjusted over-the-month change to determine what it is adding to employment?
No, birth/death factors are a component of the not seasonally adjusted estimate and, therefore, are not directly comparable to the seasonally adjusted monthly changes. Instead, the birth/death factor should be assessed
in the context of its effect on the not seasonally adjusted estimate.
- Can BLS provide an estimate of the contribution of the birth/death adjustment to the seasonally adjusted monthly payroll change?
BLS does not calculate an estimate of the seasonally adjusted contribution of the birth/death model. The sample, the imputation of business births using deaths, and the net birth/death model are all necessary components for obtaining an accurate total
employment estimate. The components are not seasonally adjusted separately because they do not have any particular economic meaning in and of themselves.
- How frequently are the birth/death figures revised, and why do the values change?
Prior to the release of preliminary January 2011 employment estimates in February 2011,
birth/death residuals were calculated on an annual basis and then applied each month during
development of monthly estimates. With the release of the January 2011 preliminary estimates,
CES began updating the net birth/death model component of the estimation process on a quarterly
basis instead of annually. This change allows for the incorporation of QCEW data into the birth/death
model as soon as it becomes available and reduces the post-benchmark revision in the CES series.
This change does not impact the timing or frequency of CES monthly and annual releases or when benchmarking
is done. For more information on the timing and updates to the inputs for the birth/death forecasts,
please see www.bls.gov/ces/ces_quarterly_birthdeath.pdf.
- How long has CES been using the birth/death factors, and is the history of birth/death available?
Implementation of the birth/death factors was associated with the implementation of a new probability-based sample design and estimator.
The new methodology was phased in gradually under the following schedule: beginning in June 2000 (with the March 1999 Benchmark),
wholesale trade on an SIC-basis was under the new methodology; in June 2001 (with the March 2000 Benchmark), mining, construction,
and manufacturing on an SIC-basis were added; in June 2002 (with the March 2001 Benchmark), all of total private with the exception of
services were under the new methodology; with the conversion to NAICS in June 2003 (with the March 2002 Benchmark), all of the total
private industries were produced under the new methodology.
Historical birth/death factors are available at www.bls.gov/web/empsit/cesbdhst.htm.
- Were estimates purely sample-based before 2003?
No, prior to the implementation of birth/death modeling, CES used a technique known as bias adjustment to account for business births, business deaths, and other limitations of the survey.
More information about the bias adjustment model and the CES transition to the birth/death model is available in the 2002
Benchmark Article, available at: www.bls.gov/ces/cesbmart02.pdf.
Last Modified Date: February 5, 2016