Summary of internal migration for Scotland, quality assurance of administrative data used in population and migration statistics: January 2018

• The internal migration for Scotland data refer to the number of people moving between Scottish council areas within Scotland.

• These data are used in our UK mid-year population estimates, internal migration estimates and local area migration indicators suite.

• We are providing a basic level of assurance for these data, having made an assessment in terms of risk to quality and the profile of the statistics in which they are used, please see the Quality assurance of administrative data (QAAD) Toolkit for more information.

• This is a summary report; please refer to the full population and migration statistics QAAD report on internal migration for Scotland for more information.

The internal migration for Scotland data refer to the number of people moving between Scottish council areas (equivalent to England and Wales local authorities). It also covers the movement of people into Scotland from other constituent countries of the UK.

The NHS Central Register (NHSCR) for Scotland records the movement of patients between NHS Health Board areas within Scotland. The Community Health Index (CHI) is a register of patients registered with a doctor in Scotland and records changes in patient addresses. National Records of Scotland (NRS) use the NHSCR for Scotland to estimate moves between NHS Board areas in Scotland, which are considered the best estimates of internal migration within Scotland.

The NHSCR for Scotland is used with the CHI to estimate moves below NHS Board level, including moves between Scottish council areas. The CHI contains postcode information, which allows geographical information to be assigned to patient records. Estimates below NHS Board level are constrained to the NHS Board level figures, so that they are consistent with moves across NHS Board areas.

The internal migration for Scotland data are used by Office for National Statistics (ONS) in population and migration statistics to show the movement of people within Scotland between Scottish council areas and for moves to Scotland from other constituent countries of the UK.

They are National Statistics produced by National Records for Scotland (NRS) and are used by ONS for the purpose for which the data are created.

They are used in the components of population change tables for the UK local authorities within the UK mid-year population estimates, internal migration estimates and in the migration flows table within the local area migration indicators sutie (LAMIS). The teams who produce the mid-year population estimates and LAMIS use the data to measure both migration between Scottish council areas and moves to Scotland from other constituent countries of the UK. The team who produce internal migration estimates use the data to measure moves to Scotland from other constituent countries of the UK only.

There is no direct source for estimating internal migration in the UK. It is, therefore, necessary to use proxy data to produce estimates of internal migration. Research indicates that the NHS Central Register (NHSCR) for Scotland and Community Health Index (CHI) data are the best proxy sources of internal migration estimates for Scotland. Recent improvements in the data have included making the statistically accepted delay in registration with a doctor in the CHI consistent with that in the NHSCR for Scotland. Previously it had been three months instead of two months. There are also strong links between the NHSCR for Scotland team and the CHI data providers.

For moves between the constituent countries of the UK, the receiving country is deemed to have the best data and as such determines the flows from the other constituent countries. This is due to a known issue where people do not de-register with their GP surgery when moving (so can be seen as passive) and registration requesting access to services is an active event. The other UK countries then agree to the totals to ensure consistency.

Migration within Scotland is estimated based on General Practitioner (GP) registration and so will only pick up migrants who register with a GP at their new address. A particular group of migrants who are unlikely to register are wealthy migrants who only access private healthcare.

A known weakness of patient registers, such as NHSCR for Scotland and CHI, is the lack of registration of young people following a move. Young men are less likely to register with a doctor and young people are less likely to tell their doctor if they have moved, including moving abroad. Plans to improve the capture of the movement of young people include looking at student moves.

The quality assurance of administrative data (QAAD) reports are designed to provide reassurance to those who use our statistics, that the data that they are built on are fit for purpose and of suitable quality. There is a QAAD toolkit, available to help guide statistical producers in the determination of the levels of assurance that we should be providing based on the risk of quality concerns to input data and the profile of the subsequent statistics.

Within Office for National Statistics (ONS), internal migration for Scotland was assessed by relevant teams and the results of those assessments are that a basic level of assurance (A1) should be provided.

The full quality assurance of administrative data (QAAD) report on internal migration for Scotland related to this summary provides further information, as well as details on where to provide feedback should you wish to do so.