Preparing your data set can involve many steps and lots of research on how the data set is organized. You will need to know the names of your variables, how they are coded, and how they are referenced in the data set. This information should be available online or in the handbook. Some things to consider about each variable:

• Is the variable a character? Numeric? Categorical?
• If the variable is categorical, what does each category represent?
• Is the variable referenced in code differently than it is labeled in output? http://www.cdc.gov/nchs/tutorials/Nhanes/Preparing/FormatLabel/intro.htm_
• How do you create new variables from old ones?
• How do you create and store smaller data sets from bigger ones for quicker manipulation and estimation (i.e. removing variables that will not be used). http://www.cdc.gov/nchs/tutorials/Nhanes/Preparing/AppendMerge/intro.htm

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