[CTPP] ACS 2005-09 data

Hello I was wondering how do you handle combining different geographic areas with each other to form a regional profile. For example, my office is a regional planning organization that serves 12 counties. I want to take the profile data from ACS 2005-09 5-year estimates for each county and form a profile of my regional, I know how to combine the estimates and do the percentages, but how do I handle the margin of error columns? Is there their a reference or guidance on this? Thank you Jason Jason Gillow Research/Planning Specialist II Ohio Valley Regional Development Commission 9329 St Rt 220 E, Suite A Waverly, OH 45690 Phone: 740-947-2853 or 800-223-7491 (In Ohio) Fax: 740-947-3468 www.ovrdc.org Email: jgillow(a)ovrdc.org