The quinquennial censuses of business establishments conducted by the Bureau of the Census are subject to nonresponse, for which imputation procedures are used to compensate for the missing data and possibly reduce related biases. For this report imputation refers to an estimation procedure leading to the derivation of values for missing census data for nonresponding business establishments. The compensatory procedures that are used in the censuses for nonresponse at the establishment level vary according to the census and item under consideration. However, they usually involve the direct use of administrative data for missing census items or imputation based on previous census and survey data and estimates of plausible period-to-period changes in the activity of the establishments. Administrative data refer to data for the designated census items that have been compiled from Internal Revenue Service (IRS) and Social Security Administration (SSA) files and stored in the Standard Statistical Establishment List (SSEL) database maintained by the Census Bureau’s Economic Programming Division. The imputed data cited in the report are derived from the SSEL, but are revised, if necessary, and maintained by the Business Division. These data reflect the results of imputation for item and establishment nonresponse and the editing or correction of data that were considered erroneously reported. The values from the file containing the imputed data are used for census tabulations.