1. Methodology background


 National Statistic   
 Frequency  Annual
 How compiled  Sample based survey
 Geographic coverage  UK

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2. Executive summary

This report is part of a rolling programme of quality reports that are produced by Office for National Statistics (ONS) to accompany statistical outputs. Quality and Methodology Information reports are overview notes that pull together important qualitative information on the various dimensions of quality, as well as providing a summary of methods used to compile the output.

This output presents age-standardised suicide rates per 100,000 population and numbers of suicides for the UK, England and Wales, England, Wales, and Regions in England from 1981 to the latest period. The figures are compiled using death registration data and mid-year population estimates. Rates are standardised using the European Standard Population to ensure comparability between different areas and over time.

Suicide data for England and Wales are held by ONS and data for Scotland and Northern Ireland are supplied by National Records of Scotland and the Northern Ireland Statistics and Research Agency respectively. We collate the figures and then calculates and quality assures the rates and confidence intervals. These are disseminated annually in a statistical bulletin and an accompanying dataset.

This report contains the following sections:

  • Output quality

  • About the output

  • How the output is created

  • Validation and quality assurance

  • Coherence and comparability

  • Concepts and definitions

  • Other information, relating to quality trade-offs and user needs

  • Sources for further information or advice

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3. Output quality

This report provides a range of information that describes the quality of the data and details any points that should be noted when using the output.

We have developed Guidelines for Measuring Statistical Quality; these are based upon the five European Statistical System (ESS) quality dimensions. This report addresses these quality dimensions and other important quality characteristics, which are:

  • relevance

  • timeliness and punctuality

  • coherence and comparability

  • accuracy

  • output quality trade-offs

  • assessment of user needs and perceptions

  • accessibility and clarity

More information is provided about these quality dimensions in the following sections.

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4. About the output

Relevance

(The degree to which statistical outputs meet users’ needs.)

Suicide statistics provide an indicator of mental health and are important for monitoring trends in deaths resulting from intentional (and probable) self-harm. The statistics are widely used to inform policy, planning and research in both public and private sectors and they enable policy-makers and support services to target their resources most effectively. Main users include the Department of Health and other devolved health administrations, public health observatories, local and health authorities, academics, and charity organisations.

Each constituent country of the UK has a suicide prevention strategy in place to identify risk factors, take action via cross-sector organisations, and reduce suicide rates.

In September 2012 the Department of Health launched Preventing Suicide in England: a cross-government outcomes strategy to save lives. This strategy aims to reduce the suicide rate and improve support for those affected by suicide and was informed by an earlier Consultation on preventing suicide in England. The new strategy outlines six areas for action including reducing the risk of suicide in main high-risk groups (for example, people in the care of mental health services, people with a history of self-harm, people in contact with the criminal justice system, and adult men aged under 50 years), reducing access to the means of suicide, and supporting research, data collection and monitoring.

Following a public consultation in 2009, the Welsh Government published Talk to Me: The National Action Plan to Reduce Suicide and Self Harm in Wales, 2009 to 2014. This is based on a strategic aim “to deliver co-ordinated action across all sectors of society for improving the mental health and well-being of the population of Wales, promoting resilience within individuals and communities, delivering timely and effective services to those people identified as being at risk and thereby reducing the rate of suicide and self harm in Wales.” The aim is underpinned by seven objectives, which include promoting mental health and wellbeing, delivering early intervention, improving information on suicide and suicide prevention, and restricting access to the means of suicide.

The National Confidential Inquiry into Suicide and Homicide by People with Mental Illness – Annual Report: England, Wales, and Scotland was published in July 2012.

To support monitoring at national and regional level, the statistical bulletin Suicide rates in the UK includes figures for the UK, England and Wales, England, Wales, and regions in England (figures for Scotland and Northern Ireland are produced separately by National Records of Scotland and the Northern Ireland Statistics and Research Agency respectively).

Counts of deaths are based on death registrations in calendar years. Suicide rates are split by sex as there are large differences between males and females. Approximately three out of every four suicides in the UK are committed by men. At national level, rates are also split by broad age groups to provide additional detail. Figures for all persons and alternative age groups are available on request (subject to legal frameworks, disclosure control, resources and agreement of costs, where appropriate). Suicide rates for local areas are not routinely calculated by Office for National Statistics (ONS) because the numbers are too small in many areas in individual years to calculate robust rates. However, based on ONS data, the NHS Information Centre produce sub-national suicide rates for 3-year rolling periods.

This output only includes data for deaths from suicide. Data on attempted suicides are not routinely collected. Results from the Adult Psychiatric Morbidity Survey for 2000 and 2007 (the two most recent surveys) estimated that 0.5% of persons aged between 16 and 74 years in England attempted suicide in 2000, and 0.7% in 2007.

Timeliness and punctuality

(Timeliness refers to the lapse of time between publication and the period to which the data refer. Punctuality refers to the gap between planned and actual publication dates.)

Suicide rates for the UK are released 13 months after the end of the reference period (for example, suicide rates for 2010 were released in January 2012), following the final release of death registration data for each constituent country. These rates are published annually.

Suicide statistics for England and Wales are available approximately 6 months after the end of the reference period, as part of the first release of annual Mortality Statistics: Deaths registered in England and Wales.

The figures are based on death registrations rather than occurrences to be consistent with other mortality outputs. In England and Wales, deaths should be registered within 5 days of the death occurring. However, deaths considered unexpected, accidental or suspicious will be referred to a coroner who may order a post-mortem or a full inquest to ascertain the reasons for the death. This can lead to delays beyond the usual 5 days, to months or even years, meaning that some of the suicide statistics presented in the statistical bulletin may have occurred in an earlier year. In November 2012, we published the report Impact of registration delays on mortality statistics.

For more details on related releases, the release calendar is available online and provides 12 months’ advance notice of release dates. In the unlikely event of a change to the pre-announced release schedule, public attention will be drawn to the change and the reasons for the change will be explained fully at the same time, as set out in the Code of Practice for Official Statistics. Historically, the provisional date for release of the statistical bulletin Suicide rates in the UK has also been the final date of publication.

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5. How the output is created

The Suicide rates in the UK statistical bulletin is compiled using information supplied when a death is registered. Information about all deaths registered in England and Wales is held on the Office for National Statistics (ONS) Death Registrations Database. Further details about the information held on this database, as well as the methods used to quality assure the data, can be found in Mortality Metadata. Deaths data for Scotland and Northern Ireland are provided by National Records of Scotland and the Northern Ireland Statistics and Research Agency respectively.

All deaths are coded by ONS according to the International Classification of Diseases (ICD), which is produced by the World Health Organisation (WHO). Since 1993, we have stored the text of death certificates on a database, along with all ICD coding relating to causes of death identified on the death certificate. We use a combination of ICD codes and this text to identify death certificates that meet the National Statistics definition of suicide as outlined in the statistical bulletin.

There are two types of rates reported in this bulletin: age-specific and age-standardised. A Microsoft Excel template illustrating the method used to calculate mortality rates and 95% confidence intervals is available.

Mortality rates are calculated using the number of deaths and latest mid-year population estimates (MYPE) provided by the Population Estimates Unit at ONS. Information about the methods used to calculate MYPEs can be found in the Mid-year population estimates short methods guide.

Age-specific rates may be calculated for given age groups and are defined as the number of deaths in the age group per million (or thousand) population in the same age group. While these rates can be compared between times, places and sub-populations, the tables containing them are usually large and may be difficult to assimilate. In addition, where there are very few deaths these rates will be imprecise and may be difficult to interpret.

The figures presented in the bulletin have been age-standardised using the direct method of standardisation. In this method, the age-specific rates for each country are applied to a standard population structure to obtain the number of cases expected in each age group in the standard population. The numbers of expected cases are then added up across all age groups and divided by the total standard population to obtain a summary rate figure.

In the bulletin, the European standard population (ESP) has been used as the standard population structure. This is a hypothetical population, which is the same for both males and females, allowing comparisons to be made between sexes and geographical areas. The ESP was first introduced in 1976 and its suitability as a standard population has not been reviewed since its introduction. Demographic changes since the population was developed may mean that it is no longer representative of the European population structure and work has begun to update it.

Rates are not calculated when there are fewer than 10 deaths in a category, as rates based on such small numbers are susceptible to inaccurate interpretation.

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6. Validation and quality assurance

Accuracy

(The degree of closeness between an estimate and the true value.)

The National Statistics definition of suicide includes deaths given an underlying cause of injury or poisoning of undetermined intent. In England and Wales, it has been customary to assume that most injuries and poisonings of undetermined intent are cases where the harm was self-inflicted but there was insufficient evidence to prove that the deceased deliberately intended to kill themselves (Adelstein and Mardon, 1975). This convention has been adopted across the UK. However, this cannot be applied to children due to the possibility that these deaths were caused by unverifiable accidents, neglect or abuse. Therefore, only adults aged 15 and over are included in the figures.

Annually, there are around 30,000 coroner’s inquests held in England and Wales that conclude with a verdict. “Short form” verdicts such as accident or misadventure, natural causes, suicide and homicide make up the majority of all verdict conclusions. “Narrative” verdicts can be used by a coroner or jury instead of a short form verdict to express their conclusions about the cause of death following an inquest. In recent years, there has been a large increase in the number of narrative verdicts returned by coroners in England and Wales. We do not always have a clear indication from a narrative verdict of whether the fatal injury or toxic substance was self-administered, or if there was deliberate intent to self-harm. The rules of coding cause of death dictate that, where no indication of intent has been given by the coroner, deaths from injury or poisoning must be coded as accidents.

Age-standardised suicide rates are standardised to the European standard population to allow comparison between areas and over time for populations of different sizes and age structures. As the rates are not true values and are therefore prone to error, 95% confidence intervals are calculated to give an indication of the size of this error. Confidence intervals allow those differences that are statistically significant (the confidence limits of the two areas do not overlap) to be distinguished from those that could be the result of chance (the confidence limits overlap). Rates are not calculated when there are fewer than 10 deaths in a category, as rates based on such small numbers are susceptible to inaccurate interpretation.

For information on accuracy checks on underlying data, please see the Mortality Statistics in England and Wales Quality and Methodology Information report.

Coherence and comparability

(Coherence is the degree to which data that are derived from different sources or methods, but refer to the same topic, are similar. Comparability is the degree to which data can be compared over time and domain, for example, geographic level.)

Eurostat publishes suicide figures for European countries based on a broadly comparable definition of deaths from intentional self-harm only. These are available for all ages and rates for males and females are age-standardised to the European standard population. Age-specific rates for particular age groups are also available.

The World Health Organisation (WHO) publishes suicide figures for countries around the world. The information presented represents official figures made available to WHO by EU member states or by their national officers responsible for suicide prevention. In turn, these are based on actual death certificates signed by legally authorised personnel, usually doctors and, to a lesser extent, police officers. Although they are not all directly comparable or timely, the suicide figures published by the WHO give an overall perspective of the extent of suicide deaths around the world.

The methodology used to calculate results for the latest and historical bulletins have remained unchanged. Age structures used to calculate rates are specific to these reports and this allows for comparisons of rates to be made over time. The methodology of how rates are calculated has also remained consistent, using the European age-standardised method where the age groups used for deriving the standardised rates are those defined by the European standard population.

Deaths of non-residents are included in the figure for England and Wales, but excluded for England and Wales figures when presented separately. Therefore, the sum of the number of deaths in England and Wales separately does not equal the figure for England and Wales combined. Figures for individual countries have been calculated using consistent methods and definitions over time and are therefore comparable.

In the UK, causes of death are coded according to the International Classification of Diseases (ICD) produced by WHO. The Ninth Revision of ICD was used in Scotland until 1999 and in England and Wales and Northern Ireland until 2000. The Tenth Revision has since been in use. Consequently, for the year 2000, results for England and Wales are not directly comparable with those for Scotland.

The suicide statistics presented in the Suicide rates in the UK statistical bulletins are not always comparable with those produced by other countries because definitions and suicide registration methods vary. For example, deaths from injuries and poisonings of undetermined intent are included in UK suicide figures based on the assumption that these deaths were self-inflicted but there was insufficient evidence to prove that the deceased deliberately intended to kill themselves (Adelstein and Mardon, 1975).

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7. Concepts and definitions

(Concepts and definitions describe the legislation governing the output and a description of the classifications used in the output.)

The National Statistics definition of suicide includes deaths given an underlying cause of intentional self harm or an injury or poisoning of undetermined intent. In England and Wales, it has been customary to assume that most injuries and poisonings of undetermined intent are cases where the harm was self-inflicted but there was insufficient evidence to prove that the deceased deliberately intended to kill themselves (Adelstein and Mardon, 1975). This convention has been adopted across the UK.

Although coroners can legally return a verdict of suicide for people aged 10 and over, the inclusion of undetermined intent deaths into the definition of suicide means the definition cannot be applied to children due to the possibility that these deaths were caused by unverifiable accidents, neglect or abuse. Therefore, only adults aged 15 and over are included in the figures.

In the UK, deaths are currently coded using the International Classification of Diseases, Tenth Revision (ICD-10). The codes used to define the suicide figures presented in this bulletin are detailed in this section.

ICD-10 codes

X60–X84: intentional self-harm Y10–Y341: injury or poisoning of undetermined intent Y87.0 and Y87.22:sequelae of intentional self-harm, injury or poisoning of undetermined intent

Notes for ICD-10:

  1. Excluding Y33.9 where the coroner’s verdict was pending in England and Wales, up to 2006. From 2007, deaths that were previously coded to Y33.9 are coded to U50.9.

  2. Y87.0 and Y87.2 are not included for England and Wales.

ICD-9 codes

E950 to E959: intentional self-harm E980 to E9891: injury or poisoning of undetermined intent

Notes for ICD-9:

  1. Excluding E988.8 for England and Wales
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8. Other information

Output quality trade-offs

(Trade-offs are the extent to which different dimensions of quality are balanced against each other.)

Suicide statistics are based on deaths registered in a particular calendar year, rather than the year the death occurred. This allows more timely publication of the statistics. The disadvantage of using registration-based figures is that it is harder to examine the relationship between suicides and other, external factors. Further information about the delay between occurrence and registration is available in the report Impact of registration delays on mortality statistics.

Assessment of user needs and perceptions

(The processes for finding out about uses and users, and their views on the statistical products.)

We welcome feedback from users on the content, relevance and format of our outputs and user feedback is requested at the bottom of all emails sent by customer service teams within the division.

Feedback is also received through regular attendance of our researchers at user group meetings and conferences. In addition, the views of a wide range of users were sought as part of the UK Statistics Authority assessment of mortality statistics.

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9. Sources for further information or advice

Accessibility and clarity

(Accessibility is the ease with which users are able to access the data, also reflecting the format in which the data are available and the availability of supporting information. Clarity refers to the quality and sufficiency of the release details, illustrations and accompanying advice.)

Statistics on suicides can be accessed free of charge on the ONS website.

Provisional release dates are announced on the release calendar 12 months in advance and final dates at least 4 weeks in advance. This enables equal access to these statistics for all users and signposts the location of the statistics on the ONS website.

The bulletin contains a summary of government policy relating to drug-related deaths and also information on users and uses of the data. It also includes statistical commentary, which describes the data and offers explanations of important trends. This narrative helps users to interpret and make appropriate use of the statistics.

Our recommended format for accessible content is a combination of HTML web pages for narrative, charts and graphs, with data being provided in usable formats such as CSV and Excel. We also offer users the option to download the narrative in PDF format. In some instances other software may be used, or may be available on request. Available formats for content published on our website but not produced by us, or referenced on our website but stored elsewhere, may vary. For further information please contact us via email at mortality@ons.gsi.gov.uk.

More information regarding conditions of access to data is available:

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Contact details for this Methodology