Sample Design
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Purpose
Just like continuous NHANES, NHANES II also uses a complex, multistage, probability sampling design, and the two surveys share many common features in sample design. Researchers need to take this into account in their analyses by appropriately specifying the sampling design parameters.
This can be done using any statistical software that can analyze complex survey designs. Specifying sampling design parameters using SUDAAN and SAS Survey procedures is presented in this module.
Task 1: NHANES II Sample Design
NHANES II data are not obtained using a simple random sample. Rather, a complex, multistage, probability sampling design is used to select participants representative of the civilian, non-institutionalized US population. Oversampling of certain population subgroups is done to increase the reliability and precision of health status indicator estimates for these groups. A detailed chapter on the sample design for the NHANES II can be found in the NCHS series report titled "Plan and Operation of the Second National Health and Nutrition Examination Survey 1976-80."
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For NHANES II datasets, the use of sampling weights and
sample design variables is recommended for all analyses
because the sample design is a clustered design and
incorporates differential probabilities of selection. If you
fail to account for the sampling parameters, you may
obtain biased estimates and overstate significance levels.
Task 2: Specifying Sampling Parameters in NHANES II Using SUDAAN or SAS Survey Procedures
SUDAAN and SAS are statistical software packages that can be used to analyze complex survey data such as NHANES II.
- Key Concepts about Specifying Sample Parameters in NHANES II using SUDAAN and SAS Survey Procedures
- How to Use SUDAAN Code to Specify Sampling Parameters
- How to Use SAS Survey Procedures Code to Specify Sampling Parameters
Page Last Modified: March 25, 2008
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