To select the correct weights for NHANES II data, you need to first check all variables in your analysis and select the weight of the smallest analysis subpopulation. Separate weights are provided for those who have completed the interview, MEC exam, or are part of one of the six subsamples. See the Table below for the correct weights for each component or subsample.
|Medical history interview final weight, N2AH0288||Use only in conjunction with the sample interviewed at home, and only with items collected during the household interview|
|MEC Examined final weight, N2AH0282||Use only in conjunction with the sample examined at the MEC, and only with interview and examination items collected at the MEC|
|Oral glucose tolerance test final examined weight, N2AH0294||Use in conjunction with laboratory data requiring a fasting sample, such as the items from the oral glucose tolerance test|
|Lead final examined weight, N2AH0300||Use in conjunction with lead subsample and only in conjunction with items collected as part of that subsample|
|Carboxyhemoglobin final examined weight, N2AH0306||Use in conjunction with carboxyhemoglobin subsample and only in conjunction with items collected as part of that subsample|
|Bile acids final examined weight, N2AH0312||Use in conjunction with bile acids subsample and only in conjunction with items collected as part of that subsample|
|“Anemia” subsample final examined weight (folate, vitamin B12, and differential leukocyte counts), N2LB0334||Use in conjunction with anemia subsample and only in conjunction with items collected as part of the anemia subsample|
|Serum ferritin final examined weight, N2LB0328||Use in conjunction with ferritin subsample and only in conjunction with items collected as part of that subsample|
You are performing an analysis to look at the association of race/ethnicity, and poverty with previous diagnosis of diabetes. All of these variables were collected in the in-home interview.
ANSWER: You would use the medical history interview final weight for your analysis (N2AH0288).
You are performing an analysis looking at the association of race/ethnicity, age, poverty and the prevalence of high blood pressure. All three demographic variables were collected during the in-home interview. For the blood pressure variables, you only want to include the average of the two seated measurements collected during the MEC exam. MEC-examined sample persons are a subset of those interviewed in the survey.
ANSWER: You would use the MEC examined weight for your analysis (N2AH0282).
You are performing a logistic regression analysis looking at the association between fasting triglycerides and race/ethnicity, age, BMI and blood pressure on persons age 20 and over. Race/ethnicity and age were available from the in-home interview. Blood pressure and BMI came from the MEC exam. MEC-examined sample persons are a subset of those interviewed in the survey. Triglycerides were measured from those sample persons who were subsampled to do the oral glucose tolerance test and were instructed to fast for from 10-16 hours. This group is approximately half the sample of those who were MEC examined.
ANSWER: You would use the oral glucose tolerance test final examined weight (N2AH0294).
It is important to check all the variables in your analysis and use the weight of the smallest sample subpopulation. Otherwise you will not obtain estimates appropriately adjusted for survey non-response.