The resolution of discrepancies between the first and second codings determines whether recoding of the work unit is necessary. Except for the Industry and Occupation variables, much of the census coding is now automated, partly in an effort to reduce the extent of coding errors. The information on the questionnaires is key-entered onto a computer file. Two procedures are used to control the number of data capture errors . Second, a sample from each batch of documents is rekeyed and compared with the original entries.
Unsatisfactory work is identified and corrected and the remainder of the batch is rekeyed as needed.
Once captured, the data are edited where they undergo a series of computer checks to identify missing or inconsistent responses. These are replaced during the imputation stage of processing where either a response consistent with the other respondent's data is inferred or a response from a similar donor is substituted. Imputation ensures a complete database where the data correspond to the census counts and facilitate multivariate analyses. Although imputation may introduce errors, the methods used have been rigorously tested to minimize systematic imputation errors. Various studies are being carried out to evaluate the quality of the responses obtained in the 1996 Census.