I am having trouble locating something that I have found on the IPUMS site in the past, information about young children in the sample for the first few years of IPUMS-CPS micro data. I know that prior to some early date (1966?) data on children under some age (14?) was not collected. Can you tell me where that is documented?
I am also puzzled by some places that this information isn’t. For instance, NUMPREC is described as fully comparable across years. Is this an error? If not, what is the rationale for comparability between years that do and don’t count children?
Finally, I would be extremely interested if you knew of any study by anyone ever to impute children to households for these early years. I believe such imputation is necessary if we are to do adult-equivalent equal-population quantiles that reach back to these early years, as is necessary for .comparability with distribution estimates for later years.
PS You guys rock! --Andrew
You are correct that children under the age of 14 are not included in the microdata for all years (excluded from ASEC prior to 1968 and from basic monthly data prior to 1982–though they are in a few supplement-containing months in the 1976-1981 time period). This is documented in the basic monthly sample notes and ASEC sample notes.
Regarding comparability notes for variables, I suspect that because this is a change in sample composition, including the information in the sample notes is more relevant than mentioning it in individual variables. I am also not aware of a variable that reports household or family size in samples that omit children (the most logical place for this information). Although NUMPREC is often the same as household size, it specifically reports the number of person records in the data file that follow a given household record. Because the children are not included in the data file, they do not have a record; therefore, I would not expect the variable to flag this as a comparability issue. Some of the linking variables (e.g., CPSIDP) direct users to this working paper on challenges creating linkages to leverage the panel component of the CPS, which discusses this omission as a comparability issue.
I am not aware of any work that imputes children in the CPS for these years.
Thanks Kari! I find your explanations pretty believable. Personally I think this sort of DRY (don’t repeat yourself) documentation makes more sense for computer code than for material intended to be used by human beings, as typical personal computers have working memory for two to eight million things, while human working memory holds four to seven. But I don’t expect anyone will pay much attention to my views on the matter.
Could you say a few words about the role of the DoL/Census in preparing this documentation to the role if IPUMS? Does IPUMS pretty much just pass on the documentation it gets, or does it engage in some summary or reorganization? If the latter, is there any way I can tell if the text of some documentation is Census/DoL or IPUMS? There are places where I should direct questions to the actual documentation preparer, I think. For example, looking at the within-ASEC-file documentation of the levels of different variables, there are some consistent patterns which appear to divide the variables into groups with somewhat differently formatted presentations. I have not been able to tell if these are conceptual or just historical accidents. I suspect that if I want a reliable answer I need not just a Census person, but some particular Census person.
Our documentation is based on what we can glean from the original documentation and the data. A large part of what we do is associate data provider documentation with a variable (as opposed to the typical tome of documentation that accompanies a single data file, but makes it hard to track a variable over time as you need to review each year’s documentation). That being said, we also work to synthesize available information into summary guides and link to original CPS documentation (see the Original Codebooks and Current Population Reports and Technical Papers on the previously linked summary guides page). If you have questions about specific variables or pieces of documentation, I am happy to share the information I have, and flag any questions that are best directed to the Census Bureau.