Codes and Frequencies
INCIMP4 is a variable that includes imputed values to replace missing data for the original variable INCFAM97ON2, a recoded variable of total combined family income (from all sources) in the previous calendar year. The complementary imputation flag variable IMPYFAMFLAG4 indicates whether responses in INCIMP4 were reported or imputed.
Related Variables and Sources of Additional Information
INCIMP4 is the fourth of five variables that contain imputed values for total family income. It was created as part of a set of variables that provide complete (i.e., without missing values) data on family income.
One of the purposes of NHIS data is to study relationships between income and health and to monitor health and health care for persons at different income levels. However, non-response rates are high for questions on total family income and personal earnings from employment in the previous calendar year. To obtain estimates of these variables for all survey participants, the National Center for Health Statistics created variables with values imputed for missing data for 1997 forward, using multiple-imputation methodology. The NHIS public use files with multiply imputed data consist of five files (and thus five versions of variables containing imputed values for missing data), one for each set of imputed values, to allow the assessment of variability due to imputation. For more information on the imputation methodology, see EMPSTATIMP1.
Before using the imputed income and earnings variables, researchers are strongly advised to read the NCHS 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".
The comparability of INCIMP4 (and the other INCIMP variables) over time is somewhat limited by changes in the recoded income categories. The variable is also indirectly affected by changes in how family income information was collected. For a description of these limitations and changes, see INCIMP1.
- 1997-2018: All persons.
- 1997-2018 : PERWEIGHT