Hi Nick,

The difference comes from different data sample.

As you know, ACS estimates are based on the survey samples. The upcoming 5 year CTPP will be based on same samples.

On the other hand, the LEHD incorporates diverse datasets. There exists possibility of having significant difference between ACS and LEHD.

I believe, however, Census Bureau tries to minimize the gap.

FYI, please find the link that NYCDOT under Nathan Erlbaum (who just left us in April) examined.

https://www.dot.ny.gov/divisions/policy-and-strategy/darb/dai-unit/ttss/cttp_acs

Hope this help,

Kyeongsu Kim

Census and Travel Survey

NY Metropolitan Transportation Council

199 Water Street 22nd fl

New York, NY 10038

kkim@dot.state.ny.us

1-212-383-7233

From: ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Lindeman, Nicholas (MPO)
Sent: Wednesday, June 06, 2012 4:22 PM
To: 'ctpp-news@ryoko.chrispy.net'
Subject: [CTPP] ACS/CTPP vs LEHD

I’ve sent the following query to both the ACS and CTPP but have not (yet) received a response. I was hoping someone on the mailing list might be able to provide assistance.

I’ve been working with Longitudinal Employer-Household Dynamics (LEHD)in On the Map. Specifically worker inflow/outflow analysis at the county level. I’ve discovered that there is a significant difference between the LEHD data and ACS Place of Work data from the 2008-10 3-Year ACS product. I've found that for the Middle Tennessee (Nashville) region the % of workers residing outside their home county is nearly 17 percentage points higher in the LEHD data than in the ACS data. Please see the attached table.

I've been tasked with determining the reason(s) for this difference. Any assistance you can provide would be greatly appreciated

Thank you,

Nick Lindeman

Nicholas Lindeman
Economic & Systems Data Analyst

Nashville Area MPO 
800 2nd Ave. S.

P.O. Box 196300
Nashville, TN 37219-6300
(615) 862-7198
lindeman@nashvillempo.org
http://www.nashvillempo.org