Comparability
In 1994 and 1995, the original NHIS response categories included "mentioned", "not mentioned", and "had no particular reason". Persons who responded that they had no particular reason are included among the "not mentioned" responses in the integrated IPUMS NHIS variable.
Changes in survey design (e.g. quarters or subsamples) affect raw frequencies but do not affect comparability between samples. As always, data users should apply prescribed IHIS weights. Otherwise there are no comparability issues.
