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Uncertainty in Local Authority Mid-year Population Estimates

The Uncertainty Project, part of the Migration Statistics Improvement Programme, was established to provide users with more detailed information about the quality of mid-year population estimates at the local authority level. 

It consists of two complementary work-streams:

1. Quality Indicators – to produce a table showing the relative risk of uncertainty in local authority mid-year estimates in terms of key indicator populations. 

2. Measures of Uncertainty – to develop a statistical measure of uncertainty associated with local authority mid-year estimates.

The statistical measures of uncertainty for 2002-2010 are now available as an Excel file to download and as an interactive map. Guidance on interpreting the table and interactive map is provided.

The results of the Quality Indicators work-stream for the 2010 local authority mid-year estimates are also available to download as an Excel file. 

Full details of the methodology used in generating the statistical measures of uncertainty are given in the November 2012 report, "Methodology for deriving a statistical measure of uncertainty for local authority mid-year population estimates 2002-2010". This updates the methodology that was presented in the report published in March 2012, "Uncertainty in local authority mid-year population estimates".  The methodology for deriving the 2010 quality indicators is also described in the March 2012 report.

Users should note that the statistical measures of uncertainty are a first attempt at providing such a measure with the aim of initiating discussion with users about their future development.  ONS would welcome feedback from users on both the methodology and the results.  Comments should be e-mailed to

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