### Purpose

This module addresses why weights are created and how they are calculated, the importance of weights in making estimates that are representative of the U.S. civilian non-institutionalized population, how to select the appropriate weight to use in your analysis, and how to correctly create subsets within your analysis population.

### Overview: Weighting in NHANES II

Weights are created in NHANES II to account for the complex survey design (including oversampling), survey non-response and post-stratification. When a sample is weighted in NHANES II it is representative of the U.S. Census civilian non-institutionalized population. A sample weight is assigned to each sample person. It is a measure of the number of people in the population represented by that sample person.

- Key Concepts About Weighting in NHANES II
- Examples Demonstrating Importance of Using Weights in Your NHANES II Analyses

### Task 1: Selecting the Correct Weight in NHANES II

To produce estimates appropriately adjusted for survey non-response, it is important to check all of the variables in your analysis and select the weight of the smallest analysis subpopulation.

- Key Concepts about Selecting the Correct Weight in NHANES II
- How to Select the Correct Weight for NHANES II Analysis

### Task 2: Creating Appropriate Subsets of Data for NHANES II Analyses

In order to calculate the most accurate measure of the variance estimate, it is important to properly create subsets of your data to reflect the subpopulation of interest before using weights in your analyses.

The contents in the Continuous NHANES tutorial on this topic are applicable to both continuous NHANES and NHANES II data. Please consult the main tutorial for more detailed information.

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