﻿ NHANES - NHANES I Web Tutorial - Survey Design Factors
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## Survey Design Factors Course

The Survey Design Factors course includes three modules:

Module 10. Sample Design
Module 11. Weighting
Module 12. Variance Estimation

These three modules provide an overview of the design features for the NHANES I samples, as well as how to correctly account for these design features in analyses. However, these modules are intended as a supplement to the Continuous NHANES tutorial Survey Design Factors course. It is assumed you have previously reviewed these modules.

The Sample Design module describes the complex sampling design of NHANES I, which includes multi-stage, unequal probability, and cluster sampling methods. This module also explains how to specify sampling parameters in an analysis.  The Weighting module describes how NHANES I weights are calculated to take into account survey non-response, oversampling, post-stratification, and sampling error. More importantly, this module teaches how to select the correct weights for an analysis. The Variance Estimation module offers a brief comparison of NHANES I and continuous NHANES on methods of variance estimation, estimate stability and sample design, variance units, then refer you back to the Continuous NHANES tutorial for detailed instruction.

These modules will provide analysts who are new to NHANES I with an improved grasp of the survey's sampling and weighting procedures and basic tools for calculating variance estimates.

If you are an experienced analyst who only needs specific information to help you complete an analysis on your own, you can pick and choose topics of interest from the navigation bar to the left, or from the Tutorial A-Z Index.  You may also go to the Sample Code and Datasets page to download and modify sample programs and datasets for your own use.

#### Sample Code

Annotated SAS and SUDAAN codes are presented in summary tables throughout the tutorial for the sole purpose of demonstration and explanation. These annotated codes do not comprise a complete SAS or SUDAAN program that can be readily submitted for a computer run. If you need the complete SAS or SUDAAN program corresponding to these annotated codes, please consult the 'Download Sample Code and Dataset' links listed under the tasks in the respective module.