2011 Census: Data Quality and Confidentiality Standards and Guidelines (Public)
Confidentiality practices

Confidentiality adjustment for population and dwelling counts

The population counts of small dissemination blocks with low population counts may be adjusted to reinforce the confidential nature of the data. In fact, all dissemination block population counts less than 15 will be rounded to a base of 5. This adjustment, however, will be controlled. That is, aggregates (totals) of the adjusted population counts for dissemination areas (DA) will always be within 5 of the actual values. The control will be even tighter at the census subdivision (CSD) and federal electoral district level (FED). In fact, while always being within 5 of the actual values, the adjusted population counts and the actual values agree for a maximum number of census subdivisions and federal electoral districts. Finally, all census division adjusted population counts and actual values agree, which means that the population counts for all census divisions (CD) remain unchanged.

Preventing disclosure

Prevention of direct or residual disclosure must also be addressed when determining product content. When assessing the potential for disclosure, a number of factors must be considered. The detail of individual variables, cross-classification of variables and the geographic level of the data will all contribute to the risk. For example, there may be no risk in producing households by number of persons in the dwelling and detailed groupings of age showing various characteristics of the household members for large geographic areas. However, the risk of disclosure would increase for the lower levels of geography.

The most common method used for preventing disclosure is defining content that is appropriate for a given geographic level. Increasing population thresholds or applying manual suppression, as needed, are other methods that can be employed. Since these are typically product-specific requirements, they are not part of the automated suppression systems.

Census of Agriculture tabulations

Census of Agriculture and Census of Population data are matched using geographic information, name, age and sex of farm operators. Imputation is performed to account for non-matches. Data are available for all members of households where a farm operator resides.

Census of Agriculture data include farm type, farm sales, area of crops and numbers of livestock, while the Census of Population provides data including age, sex, family structure, marital status and language of family members and household members. Both pre-planned standard products and custom tabulations are produced at the province level only. Multidimensional tables are common and usually include two or three dimensions.

Confidentiality measures include random rounding of 'counts' (e.g., number of operators, number of census families) and in some specific cases, low-bound suppression. Averages are provided unaltered. All verification of tabulations is done internally by Census of Agriculture staff before release.

For a summary of 2006 and previous censuses confidentiality rules, please refer to the 2006 Data Quality and Confidentiality Standards and Guidelines (Public).