In a continuing effort to produce high quality data, the Consumer Expenditure Survey (CE) has implemented multiple imputation of income data starting with the publication of the 2004 tables. Prior to 2004, CE has only published income data collected from complete income reporters (see glossary). However, even complete income reporters do not provide information on all sources of income for which they report receipt. This problem is reduced, but not eliminated, with the collection of bracketed income data starting in 2001. However, even bracketed data only provide a range in which income falls, rather than a precise value for that income. In contrast, imputation allows income values to be estimated when they are not reported. In multiple imputation, several estimates are made for the same consumer unit, and the average of these estimates is published.
The introduction of multiply imputed income data affects the CE published tables in several ways, because income data are now published for all consumer units, instead of complete reporters only. The most obvious result of this change is seen on the tables showing expenditures categorized by income before taxes, including by quintile. Starting in 2004, columns describing income, expenditures, and characteristics for "Total complete reporting" and "Incomplete reporting of income" no longer appear in these tables, and the column entitled, "All consumer units" appears on all income tables. This occurs because income quintiles and income ranges are no longer defined using only on data collected from complete income reporters, but instead are defined using the average of the multiply imputed values for each consumer unit. Also, in the tables showing expenditures by demographic characteristic, such as age of reference person, the footnote indicating that "Income before taxes" refers to "Components of income... derived from 'complete reporters only'" no longer appears.
Because of the implementation of income imputation, data for 2004 are not strictly comparable to those of prior years, especially for the income tables. In the 2003 CE tables, for example, nearly 16 percent of all consumer units are defined to be incomplete reporters. Income imputation allows expenditure data for these consumer units to be included in income categories from which they were previously excluded. To the extent that the incomplete reporters have different demographic characteristics, such as age of reference person, or expenditure patterns than the complete income reporters who were previously assigned to these categories, averages for demographic characteristics and annual expenditures will change. In addition, some complete income reporters who do not provide values for all sources of income for which they reported receipt will be classified in different income categories (ranges or quintiles) after imputation estimates these missing values. Again, to the extent that their demographic characteristics or expenditure patterns differ from the complete reporters previously assigned to these categories, the data in the tables will change. Furthermore, certain expenditures, such as personal insurance and pensions, are computed using income data. As a result of imputation, average annual values for these expenditures may be substantially different in the 2004 CE tables than in tables for previous years.
In addition, multiply imputed microdata require special methods for analysis. Users of the public use microdata will find guidance in the 2004 Public Use Microdata Documentation for both the Interview and Diary Surveys. Included in these documents is a description of the method used to obtain proper variance estimates for multiply imputed data. These procedures are also used to produce estimates of standard errors and coefficients of variation for multiply imputed income data in the published standard error tables available on this website.
Last Modified Date: November 29, 2005