Tim, I used Dun & Bradstreet 1990 employment data for the Houston region from 1996-1998 for my dissertation, "Firm Location and Agglomeration in Discrete Urban Space: An Empirical Study of the Spatial Distribution of Firms in the Houston Area". I had to clean up problems, such as branch vs. headquarter, company with the same name but difference SIC at different locations (such as Shell Oil), then the address accuracy, when it comes down to geocoding. I listed problems with prefix and suffix confusions, Mixed expressions of Rd., Road, Dr., St., Blvd., etc. Sequential inconsistency, spelling inconsistency, and disordering of street numbers. Finally, there were quite some records with P.O. Box numbers. There were no way those P.O. Boxed records could be geocoded. Since 1998, I had worked for the Forecast Group at HGAC from 1998 to 2002. We used InfoUSA (then ABI) for the base year employment input for the travel forecast model. I cleaned InfoUSA data, 1995, 1999, and 2001, for our region. Info USA had similar problems mentioned earlier as in the Dun & Bradstreet. However, there were major differences in the source data collections. Dun & Brad collected data through credit reports, unemployment insurance records, and other administrative records. On the other hand, InfoUSA collected data through phone books and calling to obtain employment counts. Since 2002, I have been working in the Travel Forecast model group that I didn't actually cleaning the data anymore. However, I still closed worked with the Forecast group for regular updates of the employment data. I compared Info USA data for years, 2003, 2004, 2007, 2008, etc., There are still problems with this group of data. For examples, it often missed larger employers or the number of count are not accurate. From time to time, I contact local larger employers such as hospitals, government, schools, etc., to verify employment counts. Another effective ways to verify employment is to make use of the web, especially the fact sheet, to supplemental our employment count. Hope it helps. Sharon Sharon Ju, Ph.D. Sr. Transportation Analyst H-GAC 3555 Timmons Lane Houston, TX 77027 Phone: 713-627-3200 Fax: 832-681-2522 Email: sharon.ju(a)h-gac.com From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces(a)chrispy.net] On Behalf Of Reardon , Tim Sent: Tuesday, June 28, 2011 2:15 PM To: 'ctpp-news(a)chrispy.net' Subject: [CTPP] Proprietary Employer Data -- Comments on the various providers? I have managed to assemble some funding to acquire employer data for our 164-municipality transportation modeling region in Eastern MA, and I am wondering if any of you have comments on the accuracy and utility of the various proprietary employer data sources currently available. I have been in conversations with two major providers (InfoGroup and Dun & Bradstreet) and have received sample files for certain zip codes, but it is hard to assess the accuracy or completeness of either sample. I'm wondering if anybody can offer insight on working with such data, and whether you have suggestions on choosing a vendor. We will be using it primarily to determine employment by sector at very fine geographies (250m or 1km grid cells) for land use planning and analysis. Some concerns we have already identified include: branch vs. headquarters employment, public sector employment, "paper companies" and verification, and the accuracy of the goecoded location that accompanies each record. Any thoughts are appreciated. Feel free to reply off-list if concerned about publicly trumpeting or bashing somebody's product. Thanks, Tim Reardon ___________________________________________ Timothy G. Reardon -- Senior Regional Planner Metropolitan Area Planning Council 60 Temple Place | Boston, MA 02111 617-451-2770 x2011 treardon(a)mapc.org<mailto:treardon(a)mapc.org> [cid:image001.jpg(a)01CC35A2.E1842650] Say it with a map! Find data and bring it alive at www.MetroBostonDataCommon.org! ________________________________ Please be advised that the Massachusetts Secretary of State considers e-mail to be a public record, and therefore subject to the Massachusetts Public Records Law, M.G.L. c. 66 § 10.