Calculating population counts for a given condition from NHANES follows these steps:
Note: Age standardization of the prevalence estimates is NOT performed because the population counts should be based on the crude (unadjusted) prevalence in the population.
Note: Population totals generated in NHANES can only be representative of the number of individuals with the health condition in the non-institutionalized U.S. population.
Note: 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.
Once CPS totals are combined, results should be output to a file.
Since the non-institutionalized CPS population totals are used to calculate the final sampling weights for the NHANES survey, you may wonder why you cannot just sum the final sampling weights for all sample persons with the health condition of interest, in order to arrive at population estimates for the health condition. For example, the total population estimate for a given health condition from the interviewed sample should equal the sum of the final interview weights for that health condition within the demographic domains among all interviewed persons. However, if there are a significant number of exclusions or missing data for a health condition, summing the weights will not produce an accurate population estimate. Therefore, using this method is NOT RECOMMENDED. The differences in population estimates by the calculated method versus the summed weight method are illustrated in the table below.
|Sample Domain||% U.S. Population||Correct Estimate||Incorrect Estimate|
DO NOT use the summed weight method to determine population estimates for a given health condition because the potential for exclusions or missing data for that health condition may lead to population underestimates.