E.5 WEIGHTING AND IMPUTATION

The last steps prior to estimation were to:5

  • weight the P-sample and E-sample cases to reflect their probabilities of selection;

  • adjust the P-sample weights for household noninterviews;

  • impute missing characteristics for P-sample persons that were needed to define poststrata (e.g., age, sex, race); and

  • impute residence and/or match status to unresolved P-sample cases and impute enumeration status to unresolved E-sample cases.

Weighting is necessary to account for different probabilities of selection at various stages of sampling. Applying a weight adjustment to account for household noninterviews is standard survey procedure, as is imputation for individual characteristics. The assumption is that weighting and imputation procedures for missing data reduce the variance of the estimates, compared with estimates that do not include cases with missing data, and that such procedures may also reduce bias, or at least not increase it.

For the P-sample weighting, an initial weight was constructed for housing units that took account of the probabilities of selection at each phase of sampling. Then a weighting adjustment was performed to account for household noninterviews. Two weight adjustments were performed, one for occupied households as of the interview day and the other for occupied households as of Census Day. The adjusted interview day weight was used for inmovers; the adjusted Census Day weight, with a further adjustment for the targeted extended search sampling, was used for nonmovers and outmovers. E-sample weighting was similar but did not require a household noninterview adjustment. Table E.2 shows the distribution of P-sample and E-sample weights.6

Item imputation was performed separately for each missing characteristic on a P-sample record. The census editing

5  

Cantwell et al. (2001) provide details of the noninterview adjustment and imputation procedures used.

6  

The weights were trimmed for one outlier block cluster.



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