For comparison estimates, self-reported data from the 2001-2006 National Health Interview Survey (NHIS) Sample Adult components were also analyzed. The NHIS is a household, multi-stage probability sample survey conducted annually by NCHS and fielded by the U.S. Census Bureau for the Centers for Disease Control and Prevention's National Center for Health Statistics [22]. The sample size for the combined 2001-2006 NHIS Sample Adult interview was 182,251 adults. Of these, 95.3% had BMI values based on their self-reported height and weight. The average annual response rate for the 2001-2006 NHIS household surveys was 88%; the final response rate for the Sample Adult component (for which self-response is required) was 72%.
