How does NAPP add value to the original census data?
The process of integration itself adds value to the data by fully documenting all codes and compiling all variable documentation in a hyperlinked web format. But we do many other things as well:
NAPP creates a consistent set of constructed variables for all samples. Most important are the family interrelationship “pointer” variables that indicate the location within the household of every person’s mother, father, and spouse.
NAPP is working on missing data allocation and consistency edits on important variables. This kind of data editing performs logical fixes when possible or finds a donor record that shares key characteristics with the person in question and substitutes their response for the missing variable. Allocation is a more statistically sound way to deal with missing data than simply excluding such cases from analyses.