Wouldn't it be nice if we could find the perfect travel behavior dataset? A lot of us are suffering from the ACS small sample sizes that result in large margins of error, especially when trying to look at tract geography. The ACS results are not perfect either and rely on self-reported addresses for the workplace. People who work in construction may report their work location as the place from where they get their check, and not at the actual construction site. Similarly, contract employees may report an address for their home office, even if they work at another location on a daily basis. One of the advantages of the LEHD OTM is that the number of primary job records is very large, resulting in a very large number of small area flows. Understanding the source of the work location and home location are important. In the LEHD OTM, the quality of the workplace coding varies widely from state-to-state. While the workplace is reported using administrative records (values are from the Quarterly Census of Employment and Wages and Multiple Worksite Reports), there have been many instances of many workers coded to a headquarters office. Even in states that "require" multiple worksite reporting, there is often lack of staff resources at State ESD offices to work on improving this list. For example, in the December 2010 LEHD Webinar http://lehd.did.census.gov/led/library/webinars.html , Robert McHaney reported that for a project in downtown Austin, two blocks were identified as having "very high" employment densities. These 2 locations were found to be a post office regional office, and a school district headquarters office. After editing those 2 blocks, the employment in the area was reduced from over 60,000 to about 33,000. As far as I know, there was no attempt at moving those 27,000 workers to another location, as the project was only concerned about downtown Austin. I also don't know how they subtracted the home ends for those 27,000 workers from the flow tabulation, or perhaps the project did not need this information. Also, previous research has shown problems with state government employment most likely to be coded to a state capitol address, rather than coded to a local office. So, depending on the area in which you are working, this may be more or less of a problem. The LEHD OTM data synthesis process includes assigning "workers" (job holders) to an employer location. If the employer has multiple work sites, then the worker is linked to a specific worksite based on an assignment algorithm using data from Minnesota, as Minnesota requires employers to link workers to a specific location. If there are no entries in the multiple worksite report, then the worker is linked to the single address in the QCEW. The home address of the worker generally is taken from their IRS record. This can be problematic for people like college students who have jobs at school, but continue to use their parent's address for IRS forms, and similarly, some snowbirds may take part-time jobs in their wintering location, and keep their summer address for the IRS. In addition, remember that the QCEW includes "covered employment" that is jobs covered by unemployment insurance. Therefore, self-employed and some other categories of workers are not included. This is generally estimated at about 10% of all workers. So, no matter which dataset you use, try to understand the source of the data and how the data have been (possibly) synthesized, and check/validate the results before you use them! Elaine Murakami FHWA Office of Planning 206-220-4460 -----Original Message----- From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Ross Friedman Sent: Tuesday, May 03, 2011 1:56 PM To: ctpp-news(a)chrispy.net Subject: Re: [CTPP] looking for journey to work data newer than 2000 Nancy, LEHD (Longitudinal Employment Household Dynamics) is a synthetic data set that is provided at the block level. However, noise is added to it so it is recommended that one aggregate the data up to TAZ or Tract level. There is an origin-destination file which gives an approximate route of workers. The data is accessible on the Census website at: http://lehd.did.census.gov/led/ (OntheMap Data) Currently, years 2002 through 2009 are available on this website. Hopefully, this will help with what you are looking for. Ross Marc Friedman East-West Gateway 314-421-4220 ross.friedman(a)ewgateway.org Does anyone know a source for journey to work data for small geographies (any geography really) post 2000 census? Nancy Reger, AICP Deputy Director, Transportation Mid Ohio Regional Planning Commission 111 Liberty St, Ste 100, Columbus OH 43215 P: (614) 233-4154 /E: nreger(a)morpc.org _______________________________________________ ctpp-news mailing list ctpp-news(a)chrispy.net http://www.chrispy.net/mailman/listinfo/ctpp-news