Can you combine population totals across survey cycles, or for multiple age and gender or race/ethnic subgroups?
Yes. It is possible to combine NHANES survey cycles. For example, to combine two survey cycles (e.g., 2001-2002 and 2003-2004), you must use the midpoint of each cycle, and combine them as follows: (NHANES 2001-2002 population totals) + (NHANES 2003-2004 population totals) in order to get a population total for 2001-2004. Similarly, you would do this for each of the age-, sex-, or race/ethnicity groups you wanted to combine to get a population total for that group. The only exception would be when combining NHANES 1999-2000 with 2001-2002 data. As stated in the weighting module, these survey years used a different reference population for sampling, so population totals for 1999-2002 are provided by NCHS.
Yes. It is possible to combine NHANES survey cycles. For example, to combine two survey cycles (e.g., 2001-2002 and 2003-2004), you must use the midpoint of each cycle, and combine them as follows: ½ (NHANES 2001-2002 population totals) + ½ (NHANES 2003-2004 population totals) in order to get a population total for 2001-2004. Similarly, you would do this for each of the age-, sex-, or race/ethnicity groups you wanted to combine to get a population total for that group. The only exception would be when combining NHANES 1999-2000 with 2001-2002 data. As stated in the weighting module, these survey years used a different reference population for sampling, so population totals for 1999-2002 are provided by NCHS.
