A number of measures have been produced to indicate the quality of the 2001 Census results for each local authority. These were issued as they became available.
This section brings together information on the quality of the 2001 Census in each local authority in England and Wales. Each local authority page accessed from the index at the end of this section contains links to
a profile
a population pyramid
the One Number Census quality assurance pack
quality indicators
One Number Census person and household imputation rates
question non-response rates and 95 per cent confidence intervals for the population estimates.
Profile
Contain a selection of frequently requested indicators from the 2001 Census, based on results released in or before February 2003. The data also include comparisons with national and regional averages.
Population pyramid
Display the distribution of age and sex.
One Number Census quality assurance pack
The One Number Census quality assurance process compared the Census estimates with a range of data from administrative sources. These data were used to determine the likely range within which the population could be expected to fall. The pack details the quality assurance process and the results found for each local authority. There is more information about the quality assurance process HERE.
Quality indicators
Derived from the One Number Census person imputation rates, and expressed as a four point scale based on the proportion of imputed people in an area.
Quality Indicator
Imputation rate
1
Less than 5%
2
5% and less than 10%
3
10% and less than 20%
4
20% and over
there is more information about the indicators HERE.
One Number Census imputation rates
The One Number Census identified the extent of under enumeration in the 2001 Census by conducting a large post-enumeration survey. The people identified as not counted were imputed to produce an adjusted total on which the final Census results were based. The imputation rates spreadsheets contain information on household imputation rates and person imputation rates for each local authority and ward, by key variables such as sex and age group for each local authority. There is more information HERE.
Question response rates
Provide information on the population of responding individuals who did not answer specific questions. Missing values were provided by edit or imputation. There is more information HERE.
One Number Census 95 per cent confidence intervals
The Census population estimates were based on a sample survey and are therefore subject to sampling error. The error levels can be used as a guide to the accuracy of estimates. Standard statistical techniques were used to calculate these error levels and to produce confidence intervals for the Census results. A 95 per cent confidence interval is a range within which the true population would fall for 95 per cent of the times a sample survey was repeated. If an estimate has a high error level, the corresponding confidence interval will be very wide. There is more information HERE.
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