Variable for family structure

I’m trying to look at family structure for children under 18 years.
If I want to use a variable regarding family structure, and I want to know the variables of living a single parent, both parents, grandparents, both parents and grandparents, and having siblings or not, what variable(s) should I use? Is there anything that I should be aware of, or be careful of, when using such family structure variables?

Inferring family structure from NHIS data can be complicated. To identify the different types of families you indicated, I would begin with the RELATE variable, which reports how each person in a household is related to a single reference person. Please note, however, that the values for RELATE depend on who the reference person is. For example, in a household that includes a married couple living with their adult child, the values of RELATE for the entire household change depending on who the reference person is. If the reference person is one of the parents (e.g., the mother has the RELATE value of Householder ), then the list of values for RELATE in the household will be Householder , Spouse , and Child . However, if that same household instead lists the adult child as the reference person (e.g., the child has the RELATE value of Householder ), then the values for RELATE in the same household would instead be Householder , Parent , and Parent .

To identify the types of families you listed requires identifying all possible combinations of RELATE that might exist within a household that indicate the type of family you are interested in, then writing the code to determine if the household meets any of those requirements. For example, to identify if there are grandparents in a household, it is insufficient to just search for RELATE values of Grandparent ; you would need to look for cases where there are RELATE values of both child and parent in the same household (e.g., the parent of the reference person is the grandparent to the reference person’s child). To iterate this process over all the family structures you outlined is no small feat! Here is a list of variables included in IPUMS NHIS that report information about family interrelationships. It is fairly easy to identify the number of children, number of children under 5 years old, and number of siblings a person has using existing variables. You may also find the family structure variables (FAMSTRUC1F, FAMSTRUC2F) helpful.