99 = N.I.U. (Not in Universe; No own children present in household).
YNGCH reports the age of the youngest own child (if any) residing with each individual, regardless of the child's age or marital status. The highest legitimate age for YNGCH is 85. YNGCH includes step-children and adopted children as well as biological children. Persons with no own children present are coded 99.
Note that YNGCH is an IPUMS-derived variable using IPUMS-derived family interrelationships. Thus YNGCH may differ from any family information that comes from just the ATUS.
The comparability of this variable is affected by the information available on family relationships. YNGCH is based on the information contained in AGE, RELATE (Relationship to household head), MOMLOC, MOMLOC2, POPLOC, and POPLOC2. These variables are comparable from 2003 onward.
Some RELATE categories are less clear than others, so additional restrictions are placed on creating links in MOMLOC, MOMLOC2, POPLOC, and POPLOC2. For example, the designation as an "Other relative" does not give much information about how this person is related other household members. Likewise, among "Housemates" it is unclear if or how the housemates are related to each other or not. Because these relationships are unclear, IPUMS only creates parental links for "Other relative", "Housemate" "Roomer" and "Non-relatives" when they are single and under 22. Thus, in some cases, persons whose oldest child is older than 22 may be coded as having no own children present in the household.
Comparability with IPUMS-USA
The development of new family interrelationship variables was prompted by the desire to have more comparability between different IPUMS projects and over time. The family interrelationship variables use common logic across ATUS-X, IPUMS CPS, IHIS, and USA (modern years). Each project has different allowed links because of different level of detail in each project, but the logic of assigning parents in ambiguous situations is the same.
- ATUS respondent household members.