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Family income group imputation flag 4

Codes and Frequencies

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IMPYFAMFLAG4 is a generated variable that reports whether the value in the complementary variable INCIMP4, total combined family income, was directly reported (IPUMS NHIS code 0), was imputed without any other income information (IHIS code 1), or was imputed from some information on the level of income (IHIS code 2).

Related Variables and Additional Sources of Information

The complementary variable INCIMP4 was created as part of a set of variables that provide complete (i.e., without missing values) data on family income; the accompanying flag variables allow researchers to identify in which cases imputation was used.


For more details on the purpose and methodology of imputation used in the NHIS, see EMPSTATIMP1.

Before using the imputed income and earnings variables, researchers are strongly advised to read the National Center for Health Statistics documentation on imputed income, such as 2018 Imputed Family/Personal Earnings Files and "Multiple Imputation of Family Income and Personal Earnings in the National Health Interview Survey: Methods and Examples".


IMPYFAMFLAG4 is not fully comparable over time. The meaning of the variable codes, by groups of years, is a follows:


For 1997-2006, the category labeled "family income reported" (IHIS code 0) means, according to a note in the codebook for those years, that family income was not imputed, but rather "is based on reported data (either exact income or 44-category income group)."

For 2007 forward, this same non-imputed "family income reported" category means "family income group is based on reported income (exact income)."

For 1997-2006 and for 2007 forward, the category labeled "imputed, no income information reported" (IHIS code 1) has the same meaning in all years.

For 1997-2006, the category labeled "imputed, some income information reported" (IHIS code 2) means "11-category income group was unknown (2-category income information was reported)." In other words, in 1997-2006, imputation for category 2 was based on the information that family income was above or below $20,000.

For 2007 forward, the category labeled "imputed, some income information reported" means, according to a note in the codebook for those years, that "family income group is based on imputed family income because income only range was reported."

These different meanings for imputation categories are due to changes between 1997-2006 and 2007 forward in how interviewers probed for family income information.


For 1997-2006, when respondents refused or did not know their family income, interviewers first asked whether the amount was above or below $20,000 and then asked them to pick the appropriate category from a set of grouped income intervals.

Beginning in 2007, interviewers probed for family income information using an unfolding bracket methodology. This method asked a series of closed-ended income range questions (e.g., "is it less than $50,000?"), constructed so that each successive question established a smaller range for the amount of the family's income. This shift in methodology is reflected in the changing meaning of two categories (IHIS codes 0 and 2) for IMPYFAMFLAG4.

There were also changes in the number of family income categories reported in the NHIS public use files and in the value of the topcoded category between 1997-2006 and 2007 forward. See INCIMP1 for more details.


  • 1997-2018: All persons.


  • 1997-2018