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2007/2008 Household Travel Survey. Presentation to TRB Household Travel Survey Subcommittee by Robert E. Griffiths Technical Services Director National Capital Region Transportation Planning Board Metropolitan Washington Council of Governments January 13, 2009. Sampling Plan.
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2007/2008 Household Travel Survey Presentation to TRB Household Travel Survey Subcommittee by Robert E. Griffiths Technical Services Director National Capital Region Transportation Planning Board Metropolitan Washington Council of Governments January 13, 2009
Sampling Plan • 11,000 Randomly Selected Households in TPB Region and adjacent areas • Ensure a sufficient number of samples in higher density, mixed use urban areas and Regional Activity Centers • Address-based Sample
Survey Interviewing • 14-Months of Interviewing • Interviews Conducted Between February, 2007 and March 2008. • Response Rates • 10% Recruitment Stage • 76% Retrieval Stage
Three Sample Types • Households with Known Phone Numbers (Type 21) • Advance Letter, No Incentive • Households without Known Phone Numbers (Type 22) • Advance Letter, $50 Post Interview Incentive • Household with Known Phone Numbers, but Recruited by Mail (Type 23) • Advance Letter, $50 Post Interview Incentive
Delivery & Response Rates • Type 21 – 96% Delivered, 11% Response • Type 22 – 87% Delivered, 6 % Response • Type 23 – 88% Delivered, 9% Response
Differences in Household Characteristics • Type 21 Households • 63% SF Housing • 19% MF Housing • 85% Own Home • Type 22 & 23 Households • 31% SF Housing • 50% MF Housing • 55% Own Home
Differences in Household Characteristics (cont’d) • Type 21 Households • 31% -1 Person Households • 18% - 4+ Person Households • Type 22 & 23 Households • 42% -1 Person Households • 12% - 4+ Person Households
Differences in Household Characteristics (cont’d) • Type 21 Households • 18% Household Income < $50,000 • 6% - Zero Car Households • 20% - 3+ Vehicle Households • Type 22 & 23 Households • 30% Household Income < $50,000 • 13% - Zero Car Households • 11% - 3+ Vehicle Households
Travel Characteristics • 10% of the Households Interviewed were “Cell Phone Only” • Unweighted Trip Rates were: • 9.2 daily trips per Household • 4.3 daily trips per Person • 6% of the Households and 12% of the Person Interviewed reported zero trips on their Travel Day
Main Conclusion • Address List Sample and Mail Recruitment results in the collection of travel survey from households underrepresented in telephone only surveys