STATA 11 for Windows SAMPLE SESSION - Food Security Group ...

Stata 11 Sample Session Section 3 – Tables and other Types of Analysis
Indicator variables
[type_of_weight=variable_in_file].
Let’s use one of the Stata’s sample data files to explore this subcommand.
1. Click on File then Open A dialog box should open
telling you that the data have changed and do you want
to continue and lose unsaved data. We don’t want to
save any changes to the data file, click on Yes
2. Select census.dta.
3. Click on Ok. - Remember to copy the command and
paste it into the do-file editor.
Use the Browse button to look at the data. There is one
observation for each state. The variable called pop is the total
population for the state. The variable called medage is the
median age of the population. First let’s get the populationweighted
mean.
1. From the Statistics menu select Summaries, tables
& tests then Summary and descriptive statistics
then Summary statistics
The Summarize - Summary Statistics dialog box opens.
2. Select medage in the “variables” box.
3. Click on the “weights” tab.
Note that only 3 types of weights are available to
choose from. There is also a help button on weights.
4. Select Analytic weights
5. Click on the copy button, switch to the do-file editor,
paste the command, switch back to the dialog box and
click on Submit.
Look at the output. The sum of the weight is 225,907,472.
This is the population of the U.S. in the 1980 census. The
weighted mean is 30.11. Now, return to the dialog box.
6. Click on None under the Weight tab.
7. Click on the copy button, switch to the do-file editor,
paste the command, switch back to the dialog box and
click on Ok
The unweighted mean is 29.54. The Stata commands are:
use "census.dta", clear
summarize medage [aweight=pop]
summarize medage
Survey weights are discussed in the next section.
An indicator variable is a special case of a categorical variable.
An indicator variable has two groups only, whereas other
categorical variables can have more than two groups. Usually
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