CASEIDP is an identifying number unique to each household. All persons in a household have the same CASEIDP identifier.

CASEIDP is the same as TUCASEID which is on the public use ATUS files. For user convenience CASEIDP has been converted to a numeric variable. Users who are trying to match ATUS-X files with public use ATUS files must be sure that CASEIDP and TUCASEID are of the same type.

The combination of CASEIDP and PERNUM uniquely identifies every person in the database.

2003-2010: All persons.