Hello all,
I am working on a project that includes quantifying the number of adults impacted by cardiovascular disease. We’re using data from 1997-2018 and the samples cheartdiev, heartconev, strokev, and heartattev, which have been used in previous studies before. We have found that these questions have all been asked consistently every year from 1997-2018, yet we still have over 50% not in universe (NIU), even after removing all people under 18 from the sample we’re examining.
Does anyone know more about not in universe, and why some individuals may not have data on them? It looks like the NIU all, for what I can tell, have a sample weight of 0. Does this mean that these data were removed by IPUMS when balancing the sample weight?
From 1997-2018, the NHIS collected general information from a core questionnaire that gathered information about all household members as well as a more detailed questionnaire administered to one randomly selected sample adult and one sample child from each family. The variables that you’re using are from questions that were only administered to these sample adults. Adult family members who were not selected to complete the supplement survey will have a weight of zero for SAMPWEIGHT. This is described in our User Note on Sample Design and documented in the universe tab for each variable.
The language can be somewhat confusing and is not always self-explanatory; we offer a user guide to help familiarize researchers with the data.
Hi Ivan
Thank you so much for clarifying, this was very helpful.
Best,
Lily