Editing: Editing is a process that ensures survey data are accurate, complete, and consistent. Efforts are made at all phases of collection, processing, and tabulation to minimize errors. Although some edits are built into the Internet data collection instrument and the data entry programs, the majority of the edits are performed after the case has been loaded into the Census Bureau's database.
Edits consist primarily of two types: consistency and a ratio of the current year's reported value to the prior year's value. The consistency edits check the logical relationships of data items reported on the form. For example, if a value exists for the number of retirees receiving benefits because of age or length of service then there must be a value reported for the amount paid. The current quarter/prior quarter edits compare by item code the data reported for the current quarter with data reported for the prior quarter. If data falls out of acceptable tolerance levels, the item is flagged for review. For both types of edits, the edit results are reviewed by analysts and adjusted when needed. When the analyst is unable to resolve or accept the edit failure, contact is made with the respondent to verify or correct the reported data.
Imputation: Not all respondents answer every item on the questionnaire. There are also questionnaires that are not returned despite efforts to gain a response. Imputation is the process of filling in missing or invalid data with reasonable values in order to have a complete data set. Usable replies are received from 85 to 95 percent of the systems canvassed. Imputations are developed for each of the remaining systems in the panel based on grouping similar retirement systems and applying a growth rate to each data item for the non-responding system, based on the average growth rate of a group of systems similar to the nonrespondent. This method is based on research conducted in 2010 and was first implemented in the first quarter of 2011. A bridge study which reviews the imputation methodology in detail can be accessed here: http://www2.census.gov/govs/pubs/2011pubs/govsrr201101.pdf