What observations would be coded as observations not applicable in MIGPUMA1?

“N/A” is used to indicate “not in universe,” and the universe for MIGPUMA1 is limited to “Persons age 1+ who lived in a different house 1 year ago”. This explains why such a large portion of the U.S. population (85.6% in 2016) is coded as N/A: most lived at the same address 1 year ago.