Census tract.

A census-defined geographic area of roughly 2,500 households. Census tracts are aggregations of census blocks (roughly 150 blocks, dependent on the population of the area). Tracts are intended to be relatively stable entities over time, though their definitions do shift with each census.

Census 2000 Supplementary Survey.

Pilot program for the American Community Survey; a survey to collect data items from the census long form that was conducted in monthly samples totaling 700,000 households in 2000.


The last stage of nonresponse follow-up when enumerators are instructed to make a last attempt to obtain at least minimal information, from a proxy if necessary. Imputation is used to fill in any missing information.

Coefficient of variation.

An assessment of the variability of an estimate as a percentage of the size of the quantity being measured.

Computer-aided personal interview (CAPI).

The use of a computer to assist an interviewer in carrying out an interview. Advantages include avoiding errors in skip patterns, providing immediate edit checks, and expediting electronic data capture.

Computer-assisted interviewing (CAI).

A group of methods for using computers to assist with data collection. CAI surveys can be either interviewer-administered (conducted in person using a laptop computer or by telephone using a shared computer) or self-administered (conducted by surveys disseminated to respondents by telephone, by the Internet, or on a computer disk).

Correlation bias.

A (technical) bias in dual-systems estimation by which the estimated counts would be, on the average, either too low or too high, caused by heterogeneity in enumeration probabilities for both the census and the postenumeration survey. The heterogeneities of the probabilities for these two attempted enumerations are typically positively related, which causes the estimated counts to be on the average too low.

Coverage correction factor (CCF).

A term related to dual-systems estimation. The CCF is defined as the dual-systems estimate for a post-stratum divided by the census count (including whole person imputations and late additions); hence, it is the multiplier that can be applied to the population count for a post-stratum in a particular area to generate an adjusted count.

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