INCIMPPOINT4 is a six digit variable with no decimal places.
INCIMPPOINT4 is a variable that includes imputed values to replace missing data for the original variable INCFAM07ON, the total combined family income (from all sources) in the previous calendar year. The complementary imputation flag variable IMPYFAMFLAG4 indicates whether responses in INCIMPPOINT4 were reported or imputed.
Beginning in 2009, the NHIS has provided imputed income files that contain income dollar amount point estimates rather than income dollar groups. Because respondent confidentiality must be balanced against providing more detailed information, the variables containing the dollar amounts for personal earnings and family income have been top-coded to the 95th percentile of the distribution.
Related Variables and Sources of Additional Information
INCIMPPOINT4 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, as the technical documentation on "Multiple Imputation of Family Income and Personal Earnings in the National Health Interview Survey: Methods and Examples" describes, non-response rates are high for questions on total family income in the previous calendar year and personal earnings from employment in the previous calendar year. 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. This documentation cautions that each of the five datasets must be merged with other data from the survey to form a single completed dataset. For IPUMS NHIS data users, the imputed income files have already been merged with other data from each survey year for 1997 through the current year of data, as part of the process of adding these imputed income files and variables to the IHIS database.
The NCHS documentation for the imputed income files directs that analysis of the five versions of each imputed income variable should be done separately, using methods and software that are appropriate for such survey data (for example, SAS-callable SUDAAN or SAS-callable IVEware).
Only then can estimates and standard errors be combined using the combining rules described in the aforementioned document on "Multiple Imputation of Family Income and Personal Earnings in the National Health Interview Survey." The 2018 imputed income file documentation further warns:
Examples of correct data analyses and additional information about the procedures used to create the imputed data are provided in the technical documentation referred to above.
- 2009-2018: All persons.
- 2009-2018 : PERWEIGHT