Appendix 3: Notes, definitions and quality of statistics

General

Rounding

Figures are calculated using unrounded data.

Conventions for tables

Where a range of years is listed in a table (for example, ‘2018-19’), the information we have given will be an average for that length of time or in the case of non-census migration it will refer to migration between 1 July (2018) to 30 June (2019).

In all tables ‘year’ means ‘calendar year’ unless otherwise stated.

The date events happen and the date of registration

The statistics about births and deaths in the Population chapter are for mid-year periods (from 1 July of one year to 30 June of the next) and relate to the date the event happened and not to the date the event was registered. For example, a birth on 29 June 2019 which was registered on 4 July 2019 would be included in the mid-2019 figures, which relate to the period from 1 July 2018 to 30 June 2019.

All the other statistics about births and deaths, as well as the statistics about stillbirths, marriages and civil partnerships, are for calendar years and relate to the date the event was registered, not the date the event actually happened. For example, a birth on 31 December 2018 which was registered on 4 January 2019 would be included in the 2019 figures. By law, births and stillbirths should be registered within 21 days, marriages and civil partnerships should be registered within three days, and deaths should be registered within eight days. Almost all births, stillbirths, marriages, civil partnerships and deaths are registered on time.

The place the relevant person usually lives and the place the event happens

Births, stillbirths, and deaths are generally allocated to the area in Scotland where the relevant person (the mother for births and stillbirths, and the person who has died for deaths) usually lives. If the relevant person does not usually live in Scotland, the event is allocated to the area in which it happened. However, a death may be allocated to the area where the person used to live if the area is in Scotland and the person had lived away from that area for less than 12 months.

Marriage and civil partnership figures relate to the area where the event took place.

Age

Ages relate to the person’s age on their last birthday.

When working out average ages (such as the average age at death and the average age of mothers at childbirth) we have added half a year to people’s age at their last birthday. For example, to work out the overall average age at death, we have assumed that the average age of 77-year-olds who died was 77 years and six months.

Age standardisation

A straight comparison of rates between areas may give a misleading picture because of differences in sex and age between the different populations. For example, it would be unreasonable to expect a high birth rate in an area with a high proportion of elderly people. Because of this, we have standardised information in certain tables and charts. Standardisation allows areas with different age and sex structures to be easily compared, comparing the actual number of events that happen in an area with the total number of events that would be expected if the area had the rates of the standard population. Various standard populations can be used for age standardisation. We use both the Scottish population (for the year in question) and the European Standard Population 2013 to calculate age-standardised rates.

Lists of groups of countries

EU-2 refers to the countries that became member states of the European Union on 1 January 2007, which were Bulgaria and Romania.

EU-8 refers to the countries that became member states of the European Union on 1 May 2004, which were Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia and Slovenia.

EU-14refers to the countries that were member states of the European Union before 1 May 2004 and are still members. These are Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Portugal, Spain and Sweden.

Urban and rural classifications

‘Large urban areas’ are settlements of over 125,000 people.

‘Other urban areas’ are settlements of 10,000 to 124,999 people.

‘Accessible small towns’ are settlements of 3,000 to 9,999 people that are within a 30-minute drive of a settlement of 10,000 people or more.

‘Remote small towns’ are settlements of 3,000 to 9,999 people that are not within a 30-minute drive of a settlement of 10,000 people or more.

‘Accessible rural’ settlements are areas of fewer than 3,000 people that are within a 30-minute drive of a settlement of 10,000 people or more.

‘Remote rural’ settlements are areas of fewer than 3,000 people that are not within a 30-minute drive of a settlement of 10,000 people or more.

You can get more information about the Scottish Government Urban Rural Classification in the Methodology section of the Scottish Government (SG) website.

Deprivation

The Scottish Government produces the Scottish Index of Multiple Deprivation to define small-area concentrations of deprivation across all of Scotland. The index is based on 38 indicators in seven fields – income, employment, health, education, skills and training, housing, geographic access and crime.

You can get more information about the Scottish Index of Multiple Deprivation on the SG website.

Chapter 1 – COVID-19 Deaths

COVID-19

COVID-19 is a highly infectious respiratory disease which spread globally in 2020, causing an unprecedented public health crisis. Deaths involving COVID-19 are defined as any death where codes U07.1 or U07.2 are mentioned on the death certificate according to the WHO International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10).

Excess Deaths

Excess deaths, or excess mortality, are terms used in epidemiology and public health that refer to the number of deaths above and beyond what would be expected under ‘normal’ conditions. In this report, excess deaths are calculated by comparing the number of deaths in the current year (2020) to the average of the past five years (2015-2019).

HPS

Health Protection Scotland is the organisation that coordinates activities aimed at protecting the people of Scotland from infectious and environmental hazards. It is a part of Public Health Scotland.

Sources and quality of statistics – COVID-19 Deaths

Deaths involving COVID-19 are discussed in terms of 3 key measures:

• Deaths within 28 days of the first positive COVID-19 test.
• Deaths where COVID-19 is mentioned on the death certificate by the doctor who certified the death.
• Excess deaths.

More information on the source and quality of the data used in this chapter can be found below under the heading: Sources and quality of statistics – Deaths.

You can find more information on the quality of data for COVID-19 deaths in Scotland on the NRS website.

Chapter 2 - Population

All population figures refer to estimates at 30 June of the relevant year.

Population covered

The estimated population of an area includes all those who usually live there, whatever their nationality. Students are treated as living at their term-time address. Members of UK and non-UK armed forces stationed in Scotland are included, but UK forces stationed outside Scotland are not. Short-term international migrants (people who move to Scotland for less than 12 months) are also not included.

Population projections

Population projections are estimates for future years largely based on past trends. The Registrar General asks the Office for National Statistics (ONS) to prepare population projections with input from his own experts. The latest national projections were published in October 2019, and were based on the mid-2018 population estimates. Sub-national population projections were published in March 2019 and cover council areas, health boards, national parks and Strategic Development Plan Areas.

Sources and quality of statistics – population

Population estimates are based on the 2011 Census and are updated each year by adding one year to the age of everyone in the population and including information on births, deaths and migration (people moving to or away from an area). Births and deaths are estimated using information from the civil registration system, which is virtually complete. Migration is more difficult to estimate because there is no complete migration registration system in the UK. Further information about the sources used to estimate migration is included in Chapter 6.

There is more information about the quality of population statistics in the Mid-Year Population Estimates for Scotland: Methodology Guide and About this Publication paper for the Mid-Year Population Estimates for Scotland, available on the NRS website.

Sources and quality of statistics – population projections

More information about the quality of population projections can be found in the Uses and Limitations of Population Projections section on the NRS website.

Chapter 3 - Births

Cohort

A cohort is a well-defined group of people with a common characteristic. For example, ‘the birth cohort of 1976’ refers to the people born in that year.

General fertility rate (GFR)

The number of births per 1,000 women of childbearing age (15 to 44).

Total fertility rate (TFR)

The average number of children who would be born, per woman, to a cohort of women who experienced, throughout their childbearing years, the fertility rates for the calendar year in question.

Age specific fertility rate (ASFR)

The number of births per woman for a specific age during a set time.

Marital status of parents

‘Married parents’ means parents who are married to each other. ‘Unmarried parents’ refers to parents who are not married, or who are married but not to each other.

Sources and quality of statistics – births

Statistics about births in Scotland are produced from information collected when the births are registered. The information should be very accurate as it is almost always provided by one or both of the baby's parents, and the parent (or parents) and the registrar should check the details that will appear on the child's birth certificate before the certificate is produced. Also, each record of a birth is checked by one of our district examiners.

The statistics will cover almost 100% of all births in Scotland − because of the importance of a person's birth certificate, there will be very few births that are not registered, and they are likely to be the result of extremely unusual circumstances.

You can get more information about statistics on births from the Vital Events Births – Background section on the National Records of Scotland (NRS) website.

For general information on all vital events statistics please go to the Vital Events - General Background Information section of the NRS website.

Chapter 4 – Deaths

Cause-of-death coding

Since 1 January 2000, deaths in Scotland have been coded in line with the International Statistical Classification of Diseases and Related Health Problems (Tenth Revision), also known as ICD10. We put the underlying causes of death into classes based on information collected from the Medical Certificate of the Cause of Death (MCCD), together with any extra information the certifying doctor provides later. We also take account of changes that Procurators Fiscal tell us about.

You can get more detailed information about death certificates and coding the causes of death, and how we produce statistics of deaths from certain causes from the Vital Events Deaths - Background Information section of the NRS website.

Stillbirth

Section 56(1) of the Registration of Births, Deaths and Marriages (Scotland) Act 1965 (as amended by the Still-Birth (Definition) Act 1992) defines a stillbirth as a child born after the 24th week of pregnancy which does not breathe or show any other sign of life.

Perinatal deaths

This refers to stillbirths and deaths in the first week of life.

Infant deaths

This refers to all deaths in the first year of life.

Sources and quality of statistics – deaths

Statistics about deaths in Scotland are produced from information which is collected when the deaths are registered. Details of the causes of death come from the Medical Certificate of the Cause of Death (MCCD), and so represent the results of a doctor's clinical judgment. In some cases, the doctor, a Procurator Fiscal or a pathologist provides extra information about the cause of death later, for example following further investigations.

Other information about the person who has died will be provided by the person who registers the death (who is usually a son or daughter, sometimes a husband, wife or partner, another relative or a friend, or occasionally, someone like a police officer or a care-home manager) or the registrar can get the information from existing registration records (if the person who has died was born or married in Scotland). In a small percentage of cases, some of the information about the person who has died may not be complete or accurate (for example, if the person registering the death did not know the person very well, and the registrar could not get details from previous registration records). The person registering the death and the registrar should check the details before the certificate is produced. Also, each record of a death is checked by one of our district examiners.

The statistics will cover almost 100% of all deaths in Scotland, as a cemetery or a crematorium will not accept a body unless the death has been registered. However, occasionally a death may not be recorded (for example, because the authorities do not know that someone who is missing has died).

You can get more information about statistics on deaths from the Vital Events Deaths – Background Information section of the NRS website.

You can also get some general information on all vital events statistics from the Vital Events – General Background Information section of the NRS website.

Chapter 5 - Life expectancy

Period Life expectancy

The average number of further years a person can expect to live based on the age specific mortality rates for their area and time period. Life expectancy can be calculated at all ages but is most commonly referred to in relation to life expectancy at birth.

Healthy Life expectancy

The average number of further years that a person can expect to remain in ‘good health’. The age specific prevalence of good health is estimated from survey data and assumed to remain constant throughout the person’s life.

Sources and quality of statistics – life expectancy

The life expectancy estimates are based on the projected trends in the number of deaths, formulated using the death records from the previous three years. For example, the estimates based on the figures for 2017-2019 for administrative areas were published in September 2020. Population data is drawn from the mid-year population estimates and population estimates in small areas. Self-assessed health data comes from the health question in the Annual Population Survey.

You can get more information about the quality of statistics on life expectancy in the Life Expectancy for Scotland: Methodology Guide (PDF document) and on the Life Expectancy at Scotland Level Methodology page both available on the NRS website.

Chapter 6 – Migration

Net migration

The difference between the number of long-term migrants entering Scotland and the number of long-term emigrants leaving the country.

Long-term migrant

Someone who changes their usual country of residence for a period of 12 months or longer.

Sources and quality of statistics – migration

Estimates of internal migration (that is, people moving between Scotland and the rest of the UK) are based on General Practitioners (GP) registrations and are considered reasonably accurate for most groups. They may be less accurate for young men, as they tend not to register with a GP immediately after moving.

The National Health Service Central Register (NHSCR) system records the movements of patients between NHS Board areas in Scotland. Anonymised extracts from the National Health Service Central Register (NHSCR), linked with Community Health Index (CHI) postcodes that are shared by NHS National Services Scotland with NRS NHSCR are used to calculate moves between NHS Board areas within Scotland.

The CHI holds records of people registered with an NHS doctor in Scotland. Unlike the NHSCR, these records contain the postcode of the patient's address. Migration at council area level and below is estimated using anonymised data from the CHI supplied with the permission of the Scottish Directors of Public Health.

Cross-border migration estimates (that is, people moving from one constituent country of the UK to another) are also based on patient records. The NHSCR system records the movements of patients between NHS Board areas in Scotland, whereas the movements for patients in England and Wales are recorded in the Personal Demographic Service (PDS). The PDS holds the master demographics database for the NHS in England and Wales. Each time a patient transfers to a new NHS doctor in a different NHS Board area, the NHSCR and PDS are 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 between Scotland and the rest of the UK. Estimates from the country receiving the migrants are said to be more accurate, due to the fact that someone is more likely to register with a new GP than de-register with their old GP. For this reason, estimates from the PDS are used to measure migration flows from Scotland to England and Wales, and health card data from the Health and Social Care Northern Ireland (HSCNI) database is used for moves to Northern Ireland.

International migration estimates (that is, people moving between Scotland and countries outside the UK) are based largely on the International Passenger Survey (IPS), which is a small sample survey so the estimates are subject to a degree of uncertainty.

The population estimates of non-British nationals living in Scotland are sourced from the Annual Population Survey (APS). These figures differ from the official mid-year population (MYE) estimates as the APS is a household survey, so does not include most communal establishments, so will exclude students in halls of residence who do not have a parent resident in the UK. The nationality reported refers to that stated by the respondent during the APS interview (self-reported). As the APS is a sample survey these estimates are subject to a degree of uncertainty. You can get more information about the quality of statistics on migration from the Migration - Methodology page and Migration Statistics - About this Publication (PDF document) on the NRS website.

Chapter 7 - Marriages and civil partnerships

Civil marriages were introduced by the Marriage (Scotland) Act 1939, which came into force on 1 July 1940.

The Civil Partnership Act 2004, which applies throughout the UK, came into force on 5 December 2005. The act allows same-sex couples aged 16 and over to get legal recognition of their relationship. In Scotland, the first civil partnership was registered on 20 December 2005.

The Marriage and Civil Partnership (Scotland) Act 2014 came into force on 16 December 2014, allowing same-sex couples to marry.

Sources and quality of statistics – marriages and civil partnerships

Statistics about marriages and civil partnerships in Scotland are produced from information which is collected when the marriages and civil partnerships are registered. The information should be very accurate as it will be provided by both parties to the marriage or civil partnership, and the couple and the registrar will check the details that will appear on the certificate before the certificate is produced. Also, each record of a marriage or a civil partnership is checked by one of our district examiners.

The statistics cover 100% of all marriages and civil partnerships in Scotland as a marriage or civil partnership is not legally formed unless a district registrar has carried out all the legal requirements.

You can get more information about statistics on marriages and civil partnerships from the Vital Events Marriage and Civil Partnerships – Background Information section of the NRS website.

You can also get some general information on all vital events statistics from the Vital Events – General Background Information section of the NRS website.

Chapter 8 – Adoptions

The Registrar General for Scotland registers adoptions under the Adoption of Children (Scotland) Act 1930.

Sources and quality of statistics – adoptions

Statistics about adoptions in Scotland are produced from information which is received from Scottish Courts in order to register adoptions. You can get some more information about these statistics from the Vital Events Adoptions – Background Information section on the NRS website.

Chapter 9 - Households and housing

Household estimates

Household estimates are produced every year from information on occupied and empty homes taken from council tax billing systems. An occupied home is roughly equivalent to a household. The estimates are used for a range of purposes including informing local authority decisions about housing needs and providing services (including housing, planning waste collection and community care). Information on types of housing is taken from the Scottish Assessors' Portal. The latest household estimates are for 2019.

Household projections

We produce household projections (estimates for future years largely based on past trends) every two years. These are mainly used for informing decisions about future housing need and providing services. The latest household projections, covering the period 2018 to 2043, take account of the results of the population projections and the number of residents in communal establishments. They use information from the household estimates and from the last two censuses to project trends in how households are structured by type of household and by the age of the household reference person. The household reference person is defined in the census as the eldest economically active resident of the household or, if there are no economically active people, the eldest economically inactive person. The projections give an indication of what would happen if past trends continue. They do not take account of policy initiatives, or other factors that may affect future populations. Projections for small groups are likely to be less reliable than those for larger groups, and will also be less reliable for years further into the future.

Sources and quality of statistics – households and housing

Information on occupied and empty homes and on housing type comes from council tax billing systems and from the Scottish Assessors’ Association, and then goes through a thorough process of quality assurance. It is possible that not all of the information held on the billing systems is up to date. There can also be small differences in the definitions used for various categories in the billing systems. The details can change over time as a result of reviews of council tax discounts and exemptions and year-on-year differences in the way second homes and empty homes are classed by some local authorities. This can have a small effect on the percentages of homes which are classed as empty or second homes.

You can get more information from ‘Background Information’ (section 6) of the Estimates of Households and Dwellings, 2019 publication which is available on the NRS website.

Household projections are based on the numbers of people living in private households. These are estimated by taking the population projections for each year and subtracting the proportion of people living in communal establishments, such as student halls of residence, care homes or prisons. Data on the numbers of residents in communal establishments are collected from a range of data sources, depending on the establishment type. The data are chosen to represent, as closely as possible, the census definition of residence, that is those individuals ‘staying, or expecting to stay, in a residential establishment for six months or more’. Data are collected from a range of administrative data sources and surveys and refers to 2018, where possible. For some establishment types, however, no such source is available, or 2018 data is not available, and in these cases earlier administrative data or 2011 Census data is used.

You can get more details on the sources communal establishment data from the Background section of the Household Projections for Scotland (2018-based) publication which is available on the NRS website.

Chapter 10 – Statutory Registration

Registrar

An official responsible for keeping a register or official records.

Registers

Registrars maintain current registers of births, stillbirths, deaths, marriages and civil partnerships. They also conduct all civil marriages and civil partnership registrations. All births, stillbirths, deaths, marriages (both civil and religious) and civil partnerships occurring in Scotland must be recorded in these registers. The original registers are preserved and held centrally by the Registrar General.

You can find more information about registration in Scotland on the registration section of the NRS website.