How does "sample selection" work?

How does “sample selection” work?

When a user first enters the variable documentation system on the IPUMS, IHIS and NAPP web sites, most samples are selected by default. Every variable in the system will display on all relevant screens.

Users can filter the information displayed by selecting only the samples of interest to them. Only the variables available in one of the selected samples will appear in the variable lists. Sample selections can be altered at any time in your session. Selections do not persist beyond the current session.

When a user enters the extract system after selecting samples, those selections are carried into the data extract system.