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Old 10-06-2012, 06:18 PM   #67
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Default Re: Unemployment Drops Below 8%, Conservatives Cry Conspiracy

Originally Posted by shlver
After looking at the data, it does look like they did something different this year.
The same month, September 2011, the economy added 400k jobs compared to the 900k jobs during last month's report. A difference in 500k jobs only yields a difference in 40k jobs between 103k gain in 2011 and 140k gain in 2012. they did use a massively different seasonal adjustment.

This is not clear at all to me. Can you explain each of the numbers you're using here.

Originally Posted by shlver
Not sure either as the BLS refuses to reveal how they seasonally adjust numbers, but a .3% drop in unemployment rate is unlikely and I expect a revision.

Since 2003 this is has been the Seasonal Adjustment Methodology at BLS
from: BLS Handbook of Methods, Appendix A......
.....The new procedure, called X-12 ARIMA, (Auto-Regressive Integrated Moving Average) integrates ARIMA forecasting with X-11 seasonal adjustment very much like X-11 ARIMA did, but it also provides a lot of additional tools including some that enable the estimation and diagnosis of a wide range of special effects. BLS began using X-12 ARIMA for the seasonal adjustment of the establishment-survey series effective with the release of the 1995 benchmark revisions in June 1996, primarily because of the capabilities it offered for controlling for survey-interval effects as well as moving holidays.

The standard practice at BLS for current seasonal adjustment of data, as it is initially released, is to use projected seasonal factors which are published ahead of time. The time series are generally run through the seasonal adjustment program once a year to provide the projected factors for the ensuing months and the revised seasonally adjusted data for the recent history of the series, usually the last 5 years. It has generally been unnecessary to revise any further back in time because the programs which have been used have all accomplished the objective of stabilizing the factors for the earlier part of the series, and any further revisions would produce only trivial changes. For the projected factors, the factors for the last complete year of actual data were selected when the X-11 or BLS method programs were used.

It seems clear to me that BLS does reveal how they seasonally adjust numbers. And it seems the publish their methodology before applying it.

Here's the BLS document on how Season Adjustment and how to use X-12 ARIMA and how to download the X-12 ARIMA files.

Here's the document from January of this year explaining the seasonal adjustments for 2012. I can't see it saying anything about the changes for September of this year, just that when last September's number were revised they went from 9.1 to 9.0
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