Re: [CTPP] (no subject)

Hi, Sulabh CTPP 2006-2010 is period estimates. For average autos,. the estimates means average autos owned over a five-year period. Due to economic recession starting with the year of 2007, it’s hard to say if the 2006-2010 average autos are much closer to the year of 2008 or to the year of 2010. There is no certain answer here. There are several tables in the CTPP 2006-2010 which include vehicles information. If users are interested in the aggregate number of vehicles in households, they can use Table B111103 - Aggregate Number of Vehicles Available in Households. The potential issue is that Table B111103 uses the privacy protected ACS microdataset, whose weights are adjusted for workers and not households. There is another table, Table A111102. which is a univariable distribution of Vehicles Available. As part of CTPP utility project funded by AASHTO, we compared Table B111103 and Table A111102 and no substantial differences have been identified for aggregate number of vehicles between the perturbed and real surveyed data for big geographies. But the data reliabilities for Table B111103 in small geographies, such as TAZs, are not validated yet. Hope this helps. Liang ________________________________________ From: ctpp-news-bounces(a)chrispy.net [ctpp-news-bounces(a)chrispy.net] on behalf of Sulabh Aryal [saryal(a)richmondregional.org] Sent: Monday, February 03, 2014 11:46 AM To: ctpp-news(a)chrispy.net Subject: [CTPP] (no subject) Hello everyone, We here in Richmond MPO are developing the Socioeconomic data for our Long Range Transportation plan. One of the important components of the data is the total number of automobiles (CTPP Table B111103) by Traffic Analysis Zones (TAZs). We have in the past used both the CTPP data and the Virginia DMV registration data to calculate autos by TAZs. Here are the problems we are facing this time around. The base year for our socioeconomic data is 2012. CTPP data is a rolling average from 2006-2010. How would one calculate the estimates for the year 2012 taking CTPP 2006-2008 as the base data? Assuming we do a straight line projection, how many years do we need to project the CTPP data to get the estimates for the year 2012? In other words, do we consider the CTPP data from year 2008 ( which is the mid-year) and project the data by 4 years to get the 2012 estimates or do we take the year 2010 ( which is the end year) and project the data by 2 years to get the 2012 estimates. Any insight would be appreciated. Thanks, Sulabh Aryal Associate Planner Richmond Regional Planning District Commission 9211 Forest Hill Avenue, Suite 200 Richmond, VA 23235 Phone: 804.323.2033 3 Fax: 804.323.2025 saryal@richmondregional.org<mailto:saryal@richmondregional.org> 3 www.richmondregional.org<http://www.richmondregional.org>