Table 1.

Comparison of Survey Designs

	2008 Health Tracking Physician Survey	2008 National Ambulatory Medical Care Survey
Field time	February–October 2008	2008
Sample frame	•AMA master file	AMA master file
		AOA master file
		Sample frame of CHCs developed using data from the Health Resources and Services Administration's Bureau of Primary Health Care and the Indian Health Service
Inclusion criteria	Office-based and hospital-based physicians who provide direct patient care for at least 20 hours per week	Office-based and CHC-based physicians principally engaged in direct patient care activities
Exclusion criteria	Federal employees	Federal employees
	In specialties not focused on direct patient care	In specialties not focused on direct patient care
	Residents and fellows
	Foreign medical school graduates temporarily licensed to practice in the United States
Weighted response rate	61.9%	59.6%
Mode of survey	Self-administered mail survey	One initial telephone interview and two in-person interviews
Sample design	Stratified probability sampling	Multistaged probability sampling
Geographic areas represented	50 states and District of Columbia	50 states and District of Columbia
Total sample	4,720	1,187

Sources: Centers for Disease Control and Prevention. 2008 National Ambulatory Care Survey Micro-Data File Documentation. Available at http://www.cdc.gov/nchs/ahcd/ahcd_questionnaires.htm (accessed April 5, 2011); Strouse, Richard, et al. HSC 2008 Health Tracking Physician Survey Methodology Report (Technical Publication No. 77). Center for Studying Health System Change, September 2009. Available at http://www.hschange.org (accessed April 5, 2011).