John,

I got involved with this 6 years ago, when Minnesota was the first pilot state. Maybe I can do plain English…

Census LED works with state employment agencies (Unemployment Insurance, Labor Statistics, etc.) and with Federal data sources to data-mine residential location and worksite of all covered SSNs.

State employment agencies know where everyone works (* everyone who’s legally employed, that is). And the Feds know where everyone lives, with linked SSN (again, caveats to this). This project is the fruit of the CIPSEA Act of 2002 – allows agents of the Dept of Labor, Census Bureau, other Fed agencies, to share what would otherwise be “private” or “nonpublic” data.

And the deliverable is a Census Block-level origin-destination table with a count of commuting workers (jobs). Very detailed! In fact, so detailed that Census disclosure gurus determined need to limit the detail provided in certain data elements – and to smudge or “fuzz” geographic specificity of employment worksites.

I understand discomfort with smudging, fuzzing, and simulating. Still, I’d look to this source for origin-destination pair granularity that future ACS-based CTPP will be flat-out unable to provide.

In the future, I can imagine Census LED being combined (thru Iterative Proportional Fitting) with Census ACS summaries (control totals) and ACS PUMS to produce synthetic population with detailed residence-to-worksite linkage. But this is just a dream right now, and not sure it’s a vision that others share.

-- Todd Graham

Metropolitan Council Research

651/602-1322

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Date: Mon, 6 Oct 2008 08:38:49 -0400

From: "John Hodges-Copple" <johnhc@tjcog.org>

Subject: [CTPP] seeking guidance on worker flows from the local employment dynamics On The Map data

To: <ctpp-news@chrispy.net>

Does anyone have a short, "plain English" explanation of the residence-to-workplace flows from this data and how it compares to the old long-form commuting data from the 2000 and earlier censuses (censi?). I read "synthesized" data and little red flags go up. Specifically, is this data based on actual residence and workplace data of real individuals (as with the Census), or are the residence and workplace locations from different data sources and the travel between the 2 synthesized in some way, as a travel demand model would create travel patterns between the 2?

Any guidance would be appreciated; my brief hunting through the documentation didn't give me the clear specifics I was hoping.

Thanks,

John Hodges-Copple, Planning Director

Triangle J Council of Governments

PO Box 12276

Research Triangle Park, NC 27709

919-558-9320

johnhc@tjcog.org