Codes and Frequencies
POVIMP4 is a variable that includes imputed values to replace missing data for the original variable POVERTY, which reports the ratio of family income to the U.S. Census Bureau's poverty thresholds for the year in question. Values were imputed for families who did not supply adequate income information and for families where the number of children equaled the number of family members. (See POVIMP1 for a more detailed discussion.) The complementary imputation flag variable IMPOVFLAG4 indicates whether responses in POVIMP4 were reported or imputed.
Related Variables and Sources of Additional Information
POVIMP4 is the fourth of five variables with imputed values for the ratio of family income to the poverty threshold. 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.
POVIMP4 is largely comparable over time. For 2009 forward, POVIMP1 is harmonized by the IPUMS NHIS staff from the NHIS poverty ratio variable (POVRATI2) estimated to the second decimal place and for the third decimal place for 2010 (POVRATI3).
Researchers should also be aware of changes in the methodology for collecting data on family income, which affect the original POVERTY variable and thus its imputed income POVIMP counterparts. See POVIMP1 for a description of these changes.
- 1997-2018: All persons.
- 1997-2018 : PERWEIGHT