[CTPP] New NCHRP 08-36 Report on Census Disclosure Avoidance issues

I am pleased to provide an electronic copy of the latest final report in the NCHRP 08-36 series on Task 71: Disclosure Avoidance Techniques to Improve ACS Data Availability for Transportation Planners. The report is posted at http://www.trb.org/NotesDocs/NCHRP08-36(71)_FR.pdf. The report was prepared by Cambridge Systematics. Abstract: Data dissemination rules initiated by the DRB caused significant loss of data for CTPP 2000, and are expected to cause an even more serious loss when applied to products emanating from the American Community Survey. This report summarizes the development and testing of synthetic data techniques that the Census Bureau could employ to provide alternative data, particularly in regards to journey-to-work flow data at small geography from the Decennial Census (or from the 5-year accumulation of the American Community Survey). Multi-year ACS data tables are inherently protected from potential harmful disclosure of participants, and therefore do not require further disclosure restrictions. However, if disclosure-proofing is nevertheless deemed necessary, using a form of data synthesis is probably the best approach from the viewpoint of the transportation planning data user. This research examines alternative data synthesis approaches that could be employed for multi-year ACS journey-to-work tables, including iterative proportional fitting, combined Bayesian/iterative proportional fitting, and the Generalized Shuttle Algorithm. Disclaimer: This project was conducted at the request of the AASHTO Standing Committee on Planning as part of NCHRP Project 08-36. Please note that the report did not go through the usual rigorous review process established and monitored by the Transportation Research Board Executive Committee or the Governing Board of the National Research Council, and should not be referred to as a "TRB Report". It should be described as a contractor's report conducted for the AASHTO Standing Committee on Planning with funding provided through the National Cooperative Highway Research Program Project 08-36. Regards, Nanda Srinivasan