C - D

Dependency/Dependency ratio

Dependency ratios provide simple summary measures of age composition, with respect to relative numbers of ‘dependent’ and ‘productive’ groups.

The ratios are typically based on a division of the age range into three broad, somewhat crude groupings: children, working ages and older people. For the purposes of Release 1A, the two dependency ratios used are:

  • the number of children aged under 15 per hundred people aged 15-64 (i.e. mainly those of working age); and
  • the number of people aged 65 or more per hundred of people aged 15-64.


Census data are usually produced in an aggregated form because NRS groups the information collected from individuals to produce statistics about a population.

Coverage matching process

People and households from census questionnaires were matched to people and households in the Census Coverage Survey (CCS) to identify those on both, those only on the census, and those only in the CCS. This information is used to estimate the undercount and overcount in the census.

Coverage adjustment/estimation/Coverage Assessment and Adjustment (CAA)

Coverage adjustment is the process of combining the results of the census and information gathered via a follow up survey (the Census Coverage Survey) to make a reliable estimate of those not counted in the main census. It also accounts for bias in non-response and overcount within the population. This allows a highly precise estimate of the total resident population to be made. This approach is internationally recognised.

Confidence Intervals

A confidence interval is a measure of uncertainty around an estimate from a survey, indicating the range of values within which the true (population) measure being estimated lies with a given degree of confidence. In other words the confidence interval provides the range within which (say) 95 per cent of estimates could be expected to lie if the survey was repeated. The 95 per cent confidence interval for 2011 Census population estimate of Scotland is 5,295,000 plus or minus 23,000 people.

Comparator data

A range of data was used to help quality assure 2011 Census estimates. These data included administrative sources (such as the number of people registered with a doctor) and other official NRS products (such as the mid-year population estimates).

More information is available about the wider process for quality assurance.


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