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Te Puni Kōkiri
Notes - randomisation of small numbers

The information presented in the tables in the Iwi and Rohe Profiles is based on detailed tables produced by Statistics New Zealand. Statistics New Zealand takes confidentiality of data very seriously, and there are five basic rules in place to ensure that information is only used in aggregate, and no data about individuals can be ascertained from the census data.

The geographic areas used in the profiles have been designed to accommodate these rules. For instance, each area must have a minimum population of 543 persons at every census year (2006 and 2013). This is the minimum population size required to have no data cells confidentialised under “Rule 3: Mean Cell Size”, based on the classifications which are part of the profile.

All cells in a census table are randomly rounded to base 3. This means that random adjustments are made to all cells in the table so that each number is a multiple of 3.

Table totals and subtotals will be consistent within each table but discrepancies may be observed between tables which cross-tabulate the same population by different variables. While randomisation compromises the table totals by making them appear inconsistent, this is the best available socio-demographic data. This level of compromise is not statistically significant and should not impact on decision makers making effective resource allocation and planning decisions.

Care should be taken in interpreting data that is based on small sub-groups as they are disproportionately impacted by random adjustment, respondent and processing errors.

Further information on confidentiality and random adjustment can be found in the Statistics New Zealand fact sheet: 2013 Census confidentiality rules.