On the second page of the extract interface users select which variables they want to include in their extract. Only those variables available for the particular samples selected on the first page are displayed as options. If users have selected multiple census samples, all variables occurring in any of the specified samples are displayed. Some variables have a second check box allowing users to select cases based on the value of the variable. In the future, we will add case selection boxes for many more variables.
Users can also select entire groups of related variables by checking a single box.
Only columns for selected years are displayed, with the symbols showing the availability of each variable across years. The third page provides for case selection. Only those variables chosen for case selection on the second page will appear on the third. Depending on the type of variable, the page employs one of three procedures. For simple categorical variables such as region, the user selects values from a series of check boxes.