National Records of Scotland

Preserving the past, Recording the present, Informing the future

Notes and Definitions

Notes and Definitions

Population covered

The estimated population of an area includes all those usually resident there, whatever their nationality. Students are treated as being resident at their term-time address. Members of UK and non-UK armed forces stationed in Scotland are included; UK forces stationed outside Scotland are excluded.


Population figures relate to 30 June of the year shown and ages relate to age last birthday.

Presentation of results

Although the populations are tabulated in units, this does not imply accuracy to that level. The data are presented in units for the convenience of users wishing to compile non-standard aggregations without encountering rounding problems.

Administrative areas

The composition of the health board areas in terms of council areas is summarised in the table below. Click on the links to view maps of the council areas and health board areas. These maps are 149 Kb (Adobe Acrobat Portable Document Format PDF) files.

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Composition of health board areas

Health board area

Council area

Argyll & Clyde

Argyll & Bute, East Renfrewshire(part), Inverclyde, Renfrewshire, West Dunbartonshire(part), Stirling(part)

Ayrshire & Arran

East Ayrshire, North Ayrshire, South Ayrshire


Scottish Borders

Dumfries & Galloway

Dumfries & Galloway



Forth Valley

Clackmannanshire, Falkirk(part), Stirling(part), Perth & Kinross(part)


Aberdeen City, Aberdeenshire, Moray

Greater Glasgow

East Dunbartonshire, East Renfrewshire(part), Glasgow City, North Lanarkshire(part), South Lanarkshire(part), West Dunbartonshire(part)




North Lanarkshire(part), South Lanarkshire(part), West Lothian(part), Falkirk(part)


East Lothian, City of Edinburgh, Midlothian, West Lothian(part), Falkirk(part)


Orkney Islands


Shetland Islands


Angus, Dundee City, Perth & Kinross(part)

Western Isles

Eilean Siar

*Note: In practice there are some other very small 'slivers' where health board and council area boundaries cross.

Land area

The land areas used to calculate the population density information presented in Table 7 were derived from digital boundaries used for the 2001 Census.

Migration Data Sources

Migration is the most difficult component of population change to estimate. The other components (births and deaths) are estimated using data from the civil registration system, which is considered to be virtually complete. In contrast, there is no comprehensive system which registers migration in the UK - either moves to or from the rest of the world, or moves within the UK. Estimates of migration therefore have to be based on survey data and the best proxy data that exist.  

Migration is derived from three key sources of data. The National Health Service Central Register (NHSCR) for moves between health board areas within the UK, with migration at council area level within Scotland estimated using anonymised data from the Community Health Index (CHI). The International Passenger Survey (IPS) provides information on moves into and out of Scotland from outside the UK. 

The NHSCR system records the movements of patients between NHS health board areas in the UK. Each time a patient transfers to a new NHS doctor in a different health board area, the NHSCR is notified and then the patient is considered to have made a migrant move.  Counts of these re-registrations are used as a proxy indicator for moves within the UK.

The CHI holds records of people registered with an NHS doctor in Scotland. Unlike the NHSCR, the records provided to National Records of Scotland (NRS) contain the postcode of the patient's address, which enables migration to be estimated for councils, and potentially for smaller areas. The approach used for estimating council-level migration involves matching CHI patient records which are extracted from a database which reflects the ‘live’ CHI system on two occasions one year apart.

This matching of two extracts, say A and B, will create three sets of patients:

  • set of patients in extract A and extract B
  • set of patients in extract A but not in extract B
  • set of patients in extract B but not in extract A.

The set of patients in both extracts whose postcodes were not the same in each extract can be considered as those within-Scotland migrants who moved from one address in Scotland to another within Scotland between the dates of the two extracts. The remaining two sets of patients are either migrants to or from Scotland; babies born between the two extracts; deaths between the dates of the two extracts; movements to or from the Armed Forces; and a small number of records that are for the same patient but have different CHI numbers because they could not be matched when the GP registration was processed.

Currently, NRS migration data derived from the NHSCR is considered to be the most reliable data available at health board level, so estimates from the CHI are controlled to ensure that they are consistent with the NHSCR data for moves across a health board boundary by origin, destination, age and sex.

The International Passenger Survey (IPS) is a continuous sample survey conducted by the Office for National Statistics at the principal air, sea and Channel Tunnel routes between the UK and countries outside the British Isles. The sample of migrants contacted within the survey is small, particularly for Scottish migrants (approx 120 survey contacts during 2002), and therefore estimates derived from the IPS are subject to larger sampling and non-sampling errors, and are considered less reliable than UK-level estimates. Information about the country of origin and destination, and age of migrants is particularly subject to error.  In addition to IPS data, additional information is received on migrants to and from the Republic of Ireland, asylum seekers and visitor switchers[Footnote 1].

International Migration

Under National Statistics arrangements there is a commitment to carrying out a programme of thorough reviews of key outputs, at least every five years. A Quality Review of International Migration was recently undertaken and the final report published in September 2003.

The review’s scope included all forms of migration between the UK and the rest of the world. National Statistics outputs covered by the review included both statistics relating to all migrants, and statistics relating only to those non-citizen migrants who are subject to UK immigration control. Geographical and legal aspects of migration were covered, including for immigrants, their countries of origin, routes of entry and UK destination, and for emigrants, place of last UK residence, citizenship, legal residence status and duration of stay in the UK. Also in the review’s scope were demographic, social and economic characteristics of migrants.

The review highlighted opportunities to develop and make better use of existing sources, and to develop and prepare for the exploitation of potential new sources. The review made nineteen recommendations in the broad areas of:

  • Development of better estimates of total migration flows
  • Expanded use of existing survey and administrative data sources for UK geography of migration
  • Use and development of survey and administrative data sources on persons subject to immigration control
  • New administrative sources

An implementation plan for the quality review was published in January 2004 and since then there have been a number of improvements made to the design of the IPS, including the addition of questions on intentions. There are also plans to extend fieldwork hours, to conduct a port survey of emigrants and to carry out research into non-responders to the IPS. Research is also underway comparing the distribution of immigrants in a number of sources. 

Estimates of total international migration into Scotland are published by the Office for National Statistics. The ONS estimates use a consistent methodology based primarily on the IPS to allocate migration to Scotland. The methodology is currently under review as part of the quality review, and in the meantime, a slightly different methodology is used for the purposes of population estimates in Scotland. 

Unmeasured migration

The results of the 2001 Census indicated that the previously published 2000 mid-year estimates had been overestimated by some 50,000 as a result of cumulative errors in estimating migration (mostly by young men) during the 1980s and 1990s. As a result, the migration estimates for 1982-2000 were revised. It is likely that these migration errors are the result of an underestimation of young male migration from Scotland to the rest of the world during this period, but if moves from Scotland to the rest of the UK have been under-recorded, the implied increase in overseas migration would be less.

To ensure that migration estimates do not continue to be overestimated, an adjustment was included in the 2002 and 2003 mid-year estimates. The estimated civilian migration component included an adjustment for unmeasured migration. At the Scotland level, this amounted to an outflow of -2,600.  Further investigation has shown that this adjustment should be -1,500. This element of unmeasured migration will be looked at again in conjunction with other development work on migration. Progress on work undertaken to review the quality of the method and data sources used to estimate migration have shown that the level of unmeasured migration should be reduced to -1,500. Further work will make it possible to provide historic estimates of flows between Scotland and the rest of the UK, and with overseas consistent with the revised population estimates. More information on the cumulative migration error since 1981 can be found in the NRS paper 'Comparison with Previous Estimates and Implications for Revisions' or contact Statistics Customer Services using our Contact us page. 

Further information

An explanation of the method used to produce population estimates for Scotland is available in 'Estimating Council Area Migration' on this website.


1. Visitor switchers are visitors who enter or leave the UK intending to stay in the destination country for less than a year, but who actually stay for a year or longer.

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