Updated: 29 August 2022
Next update: Not yet determined
About the statistics
The statistics contain information about the prison population per 1 January, days of imprisonments and the different types of entries, transfers and departures during the statistical year. It also provides facts about prison time, types of offences and the person’s age, sex and citizenship.
The imprisonment statistics consist of four main units; prison population per 1 January, entries, departures and days of imprisonment. Statistics Norway also publishes statistics on populations based on new imprisonments and discharges, which are broken down into type of entry and departure respectively. A person who enters and departs from prison more than once during a year will appear in the imprisonment statistics the corresponding number of times if the said entry and departure fall under the definitions of entries and departures respectively.
The figures in the imprisonment statistics consist of the following units:
Prison population per 1 January shows the number of people imprisoned at the start of the statistical year. Together with the average number of prisoners (see definition below), this unit describes the prison population in Norwegian prisons at any given time of year.
Entries to prison are either new imprisonments or re-imprisonments. A breakdown by type of entry shows the scope of new imprisonments to custody or for serving a sentence, and different types of re-imprisonments. The term “re-imprisonment” is used after an escape, failure to return after provisional leave, intermission sentence or other reasons.
New imprisonments are new remands into custody and new imprisonments to serve a sentence during the statistical year. An imprisonment to serve a sentence is due to a sanction regarding an unconditional prison sentence, preventive detention or a fine.
Transfers from custody to serving sentence are the number of departures from custody in which the prisoner is transferred directly to serving a prison sentence or preventive detention during the statistical year.
Departures from prison are either discharges or other types of departures from imprisonment. A breakdown by type of departure shows the scope of discharges from custody, from serving a prison sentence and other types of departures. Discharges from prison are further broken down into number of definite discharges or pardons, and the number of conditional discharges during the year. Other types of departure are escape, failure to return after provisional leave, intermission sentence or departure for other reasons.
Discharges are all concluded custodies and all types of discharges after serving a prison sentence (see Departures).
Days of imprisonment shows the total number of days spent in penal institutions during the statistical year. This includes days spent serving a sentence outside the penal institution, in either a treatment institution, hospital or under provisional leave. Sentences served by electronic monitoring are not included in the statistics on number of days of imprisonment.
Prison population, average number, is calculated based on the total number of days spent in penal institutions during the statistical year (see above), and shows the total number of prisoners on an average day in Norway in the statistical year (See Collection of data, editing and estimations under Production).
The units in the imprisonment statistics are broken down into the following variables and groups of variables:
Offences are defined as the acts described by law at any time as punishable. In the digital register, SSP, used as basis for the statistics on imprisonment, more than 600 different codes are in use for registering offences committed. The statistics on imprisonment are following the Statistics Norway’s’ standard classification of these codes into group and/or type of principal offence. Following the Penal Code of 2005 coming into effect on 1 October 2015, around 430 new codes were introduced into the police’ registration system for offences. These replaced the codes from the Penal Code of 1902. Consequentially, Statistics Norway now uses the new version of Standard for types of offences, Type of offence 2015, to classify both old and new codes. From the release of the year 2015 and onwards, the statistics thus contain the following breakdown of offences (see also Statistical Classifications and Code Lists – KLASS for more info):
Group of offence is a division of offences into nine main groups. These groups of offences are further divided into more specified types of offences.
Type of offence is a division of offences into about 150 unique types. Similar types of offences are grouped together to aggregated levels, where all levels are included in the nine groups of offences.
Category of offence was a classification of offences used in the statistics for the period 1993-2014, where offences were classified as either a crime or a misdemeanor. For more information on this expired classification, see the version Types of offences 2006 in KLASS.
Principal offence: If the imprisonment relates to more than one offence, it is grouped by the principal offence, i.e. the offence that, according to law, carries the most severe sentence. When these offences are classified according to the standard classification of type of offence, the terms principal offence, group of principal offence and principal category of offence are used. In the raw data received from the Norwegian Police ICT Services, the principal offence has already been ascribed for each unit (see Sources of error and uncertainty under Sources of error).
Type of imprisonment classifies the units by the different types of sanctions, i.e. custody, prison sentence (both in institution and by electronic monitoring), preventive detention and imprisonment for non-payment of a fine. Type of imprisonment is a new denomination as from 2012, and is synonymous with the variable “type of sanction” used in earlier statistics on imprisonments. The 2012 statistics contain more detailed breakdowns by the different types of imprisonments.
Custody is defined as prisoners who are imprisoned for more than three days who are not registered with other sanctions (due to missing data from SSP on the court’s decision on remand in custody). Prisoners who are imprisoned for three days or less are placed in the arrests category, and are not included in the imprisonment statistics (cf. the Criminal Procedure Act, Chapter 14, Section183; “If the prosecuting authority wishes to detain the arrested person, it must, as soon as possible and not later than on the third day following the arrest, bring him before the District Court at the place where it is most appropriate to do so, with an application that he be remanded in custody”.) When Statistics Norway receives data from the Norwegian Police ICT Services, custody is already grouped based upon the three-day criteria.
Prison sentence includes unconditional prison sentences and the anticipated serving of an unconditional custodial sentence that is not yet legally binding. Prison sentence refers to both serving a sentence in an institution and by electronic monitoring, types that are specified in tables on type of imprisonment.
Preventive detention is an indefinite sentence that may be imposed on a person considered to be legally sane and culpable, at a high risk of re-offending and a danger to society. There is no upper limit for preventive detention, which means the sanction can last for the remainder of the person’s life. Preventive detention is one of three special sanctions that were introduced on 1 January 2002 and replaced the previous arrangement for security detention. After this introduction, the units containing security detention have been classified as the same type of imprisonment as preventive detention.
Electronic monitoring means serving an unconditional prison sentence with an ankle tag outside a penal institution. Electronic monitoring is used for convicts with an unconditional sentence of up to six months (for the duration of the sentence), or for prisoners who have up to six months remaining until their expected release date (partial use of electronic monitoring). The use of electronic monitoring is excluded for particular types of offences. Persons serving a prison sentence by electronic monitoring are included in the statistics on prison population per 1 January, entries (including new imprisonments) and departures (including discharges) as from year 2008. Electronic monitoring was originally introduced as an experimental scheme in six Norwegian counties on 1 September 2008. In May 2014 the use of electronic monitoring became a nationwide scheme, with a total of 342 monitoring units in capacity. Since then the capacity on monitoring units has been expanded to a total of 500 units.
Prisoners serving a prison sentence by electronic monitoring are included under the category “prison sentence” in the statistics classified by type of imprisonment. Imprisonment by electronic monitoring is not included in the statistics showing total number of days spent in penal institutions or average number of prisoners during the statistical year.
Imprisonment for non-payment of a fine is imposed on those who default on a fine. When the court settles a case with a fine, a custodial sentence of one day to three months is also determined, which will be enforced if the fine is not paid. This is known as a default custodial sentence. Those in receipt of a fine are called on to serve a default custodial sentence if the fine is not paid within the specified deadline.
Prison time is the total time spent deprived of liberty during the imprisonment from which a person is released or transferred. This variable is measured by the number of days in closed institutions, open institutions, electronic monitoring, treatment institutions, reprimand, provisional leave and day release. Due to the definition of custody, prison time in custody is calculated from the fourth day after the arrest until the date of release from custody or date of transfer from custody to serve a sentence.
Type of deprivation of liberty is a classification that shows the scope of prison stays in either closed or open institutions, and on day release, provisional leave, reprimand or stays in hospitals or treatment institutions.
Age: A person’s age is defined as their age on 1 January in the statistical year (prison population), or per date of entry to or departure from a penal institution.
Citizenship is defined based on two different sources. Where there is a match for personal ID numbers in the Central Population Register, the person’s citizenship is derived from this source. As an example, this was the case for about 80 per cent of the prison population per 1 January 2012 and of all new imprisonments this year. For all persons who cannot be identified in the Central Population Register (by means of date of birth, personal ID number or name), information about citizenship registered by the police is used. Approximately two thirds of all non-Norwegian citizens among the prison population per 1 January and among those imprisoned during the year had their citizenship defined this way in the 2012 statistics.
The annual versions of the following Statistics Norway standards are used (see Definitions of the main concepts and variables under Definitions and Comparability over time and space under Production):
Group of offence: Standard for type of offences, version 2015, with an overview of all codes including code names. See detailed overview in KLASS.
Type of offence: Standard for type of offences, version 2015, with an overview of all codes including code names. See detailed overview in KLASS.
Age: classified by groups; 15-17, 18-20, 21-24, 25-29, 30-39, 40-49, 50-59, 60-69, 70-70+.
Topic: Social conditions, welfare and crime
Division for Income and social welfare statistics
The statistics are only published at national level (as from 1993)
The annual raw data files supplied by the Norwegian Police ICT Services (formerly the National Police Computing and Material Service (PDMT)) are stored permanently in a secured archive area. The final processed data material (i.e. the material prepared and used in the statistics production) is stored as separate archive files and documented in the DataDok system. The annual files that are used for the statistics production are also stored as SAS files, until they are no longer used.
The statistics give a description of the prison population and their principal offences during the statistical year. This is presented in figures showing the prison population per 1 January and the prisoners` entries to and transfers and departures from prison during the year. The figures also show the total number of days spent in penal institutions during the year, which forms the basis for the average number of prisoners in the statistical year.
Statistics Norway introduced statistics on imprisonments and discharges from Norwegian penal institutions in 1960. Prior to this, the Ministry of Justice produced statistics on "penal servitude institutions" and later "provincial prisons" as far back as 1875. These were replaced in 1901/1902 by an annual yearbook from the prison administration, which was published with varied regularity up to 1982. Statistics Norway expanded its imprisonment statistics in 1966 to include those held in custody and those who were imprisoned for non-payment of a fine. Until 1977, these statistics were based on individual level data with fairly detailed information on prison populations and entries to, departures from and transfers between institutions. These statistics included relatively detailed information about the units. From 1978, the imprisonment statistics were based on aggregate level data collected by the Ministry of Justice from the prison institutions. This data was mainly made up of details of the individuals' gender, type of sanction and penal institution. From 1991, individual level data with more detailed information on each unit was once again used in the statistics on the prison population per 1 January, entries and departures.
The technological tools introduced in 1999 are still in use today, and roughly the same processing procedures and definitions of the statistical units have been used since 2001. The scope of controls and discrepancy lists has gradually evolved into its current form, and this has led to a gradual improvement in the quality and degree of completion in the data sources for imprisonment statistics. This particularly applies to variables describing offences, reporting date, prison time and date of sentence. Improvements in source data and more extensive controls have also resulted in changes in the selection of data, which has led to significant breaks in the statistics’ time series – for example, before and after the year 2011 (see Sources of error and uncertainty under Sources of error).
Key users of the imprisonment statistics are the media, students, researchers, interest groups, and government agencies and bodies associated with the justice sector. In addition to this, the statistics form the basis of information for other parties with an interest in the situation and developments in the field of crime and justice.
No external users have access to the statistics and analyses before they are published and accessible simultaneously for all users on ssb.no at 8 am. Prior to this, a notice is given in the Statistics Release Calendar. This is one of the most important Principles for equal treatment of users in releasing statistics and analyses.
The imprisonment statistics are one of four main crime statistics in the area of crime and justice. The others are statistics on offences and victims reported to the police, offences investigated and sanctions. When using the crime statistics it is important to be aware that the different parts do not necessarily refer to the same population of offences within the same year. It can take a long time from an offence is reported, completely investigated and given a criminal sanction until the sentence is served. The tables on imprisonments are therefore not directly comparable with the other statistics (see the publication Kriminalitet og rettsvesen (in Norwegian only), in particular chapter 3, under Relevant documentation).
The Statistics Act, Section 10.
The statistics include the following units; entries, transfers, departures, days of imprisonment during the year and the prison population per 1 January in the statistical year. The statistics provide information on type of imprisonment (custody, prison sentence, electronic monitoring, preventive detention/security detention and imprisonment for non-payment of a fine), type of offence, prison time, type of entry, type of departure, type of deprivation of liberty in addition to age and gender.
The individual level data that forms the basis for statistics including the units’ prison population per 1 January, entries, transfers and departures, is collected from the Norwegian Central Criminal Record and Police Information System (SSP). The National Criminal Investigation Service (Kripos) is responsible for the registrations in SSP, and also provides Statistics Norway with additional information in relation to individual cases when needed. Summary data on imprisonment for non-payment of a fine and total number of days spent in penal institutions within the year is collected from the Correctional Services' computer system (KOMPIS). In addition, the Central Population Register is used to process the citizenship variable.
The scope of units and the sample quality depends on various factors, including the scope of late updates and registrations in SSP and KOMPIS, and the point in time when the data is collected from these registers (see Comparability over time and space about break in some of the time series from the statistical year 2012).
The Norwegian Police ICT Services (formerly the National Police Computing and Material Service (PDMT)) extracts data from SSP and sends it electronically to Statistics Norway. Before the statistical year 2012, the data was extracted at the end of February/beginning of March in the year following the statistical year. Due to a major restructuring, the extraction of data from the 2012 statistics and onward was undertaken at a considerably later time than for earlier years (See Sources of error and uncertainty under Accuracy and reliability). Data from KOMPIS is extracted, quality tested and delivered as summary data by the Norwegian Directorate for Correctional Services (KDI) (before 2014, by the Norwegian Correctional Services’ central administration (KSF)).
Established controls are made to the data files in order to correct errors and supply missing information. Controls on individual level data from SSP are particularly extensive, and additional information is normally collected during the second and third quarters of the year. Corrections of data from SSP are made in cooperation with Kripos, while corrections of the summary data from KOMPIS are in cooperation with KDI.
Statistics on prisoners per 100 000 population above the age of criminal responsibility only include persons aged 15 years or older as from 1990, and 14 years and older before this. Statistics on prisoners per 100 000 population where age is not specified are based on the whole population. The rates are calculated based on the population per 1 January in the statistical year. The average number of prisoners is calculated by using the number of days of imprisonment and number of days in the statistical year (365 in a normal year and 366 in a leap year).
The imprisonment statistics contain sensitive personal data and information on criminal acts that are considered to be extremely sensitive. Statistics Norway therefore administers the data sources for these statistics with great caution. When publishing statistics with few units, each case is considered with regard to the protection of personal privacy.
The main figures on the average prison population and prison population at the beginning of the year, entries to and departures from prison may be compared over time (see Background and purpose under Background). This also applies to the more detailed breakdowns of these units by gender, age and type of imprisonment.
Due to a major restructuring of the imprisonment statistics as from the statistical year 2012, the extraction of data from SSP for this and the following years were undertaken at a much later time than previous practice. Parts of the statistics from 2012 and onward are, therefore, a more complete count of the actual occurrences compared to previous years. The disparities between previous statistical years and the years 2012 and following are not of any great significance to the figures on prisoners per 1 January or the discharges. For the figures on new imprisonments and transfers made directly from custody to serving a prison sentence, and particularly with regard to the most severe crimes with a long processing time in the criminal justice system, there is a substantial break in the time series from the statistical year 2012. Further reading is available in the chapter on Accuracy and reliability.
After the new penal code (Penal Code of 2005) came into effect on 1 October 2015, the raw data from the police registers are changed. There are quite distinct differences in structure, language and content between the Penal Code of 1902 and the Penal Code of 2005, which is even more evident in the corresponding codes used for registering offences in the police’ central registration system. Code connected to both the new and the former penal code is used after 1 October 2015, due to the new legislation not having retroactive effect. Offences may be registered and processed long after they have been committed. This means that the Penal Code of 1902 and 2005 will appear in the data of all crime statistics for many years to come.
Criminal cases with violations of the provisions dating before the introduction of the new penal code (registered by former codes and appellation), will not always be possible to specify and classify in the same way as criminal cases with a violation of a corresponding provision from the Penal Code of 2005. Certain types of offences in Standard for types of offences 2015 will therefore exclusively contain violations of offences stemming from new penal legislation, and mainly consist of offences committed after 1 October 2015. In the standard, these will be indicated with “(from 1.10.2015)” in the classification name. Older offences which cannot be specified in the same way are placed in “other or unspecified” types of offences. The content of the statistics – and the possibilities of doing comparisons on the most detailed levels of the standard – will for certain types of offences therefore be mainly based on offences committed after 1.10.2015. This type of break in the time series will vary over time for the different types of offences, depending on which crime statistics you use. When such breaks in the time series are identified, the general recommendation is to use figures on a more aggregated level, which means less specified figures with a smaller degree of time series break. Se Standard for type of offences 2015 in KLASS and the article “The New Crime Statistics” (in Norwegian only).
At the same time, other factors also affect the level of comparison; the summary data on imprisonment for non-payment of a fine cannot be broken down into type of offence or age, and prison sentences served by electronic monitoring are not specified in all figures. In addition, some units have unknown offences. Statistics Norway has not published statistics grouped by each standard of offence every year (see archive for previous statistics on imprisonments). The extent of the unspecified categories has varied from year to year, and presents a challenge when comparing type of offence over longer periods of time.
The introduction of new departure codes in 2001 resulted in a break in the time series for statistics on departures as from 2001. The figures for entries and new imprisonments are not affected by this change. More stringent controls on reporting dates introduced in 2001 ensured removal from the statistics of prisoners who were registered as entering prison but not departing and thereby wrongly included in the data source. This was reflected in Statistics Norway's statistics on prisoners per 1 January, but does not affect the statistics on the average number of prisoners since this data is extracted from a different register (KOMPIS).
When Statistics Norway receives the raw data, the principal offence is already determined and registered by Kripos in SSP. The principal offence is determined by the severity of the crime and by the sentencing framework, which is also Statistics Norway’s method for classifying principal offences in the other statistics on criminals. Due to an insufficient overview of Kripos` registration practice, Statistics Norway cannot rule out the possibility that the practice varies between cases and crime statistics.
An analysis of two different 2011-data sets extracted from SSP at two different points in time in 2012 shows, in part, extensive registration of data after the point in time Statistics Norway normally receives raw data. This especially relates to registrations of new imprisonments to custody and transfers from custody to serving a prison sentence; changes that to a great extent relate to the most serious crimes. There are several aspects of these cases that make them vulnerable to registration at a later time, particularly because they take a long time to process in the justice system.
From the statistical year 2012 and onward, the extraction of data from SSP has been undertaken at a later time then previous practice, in order to obtain better data quality. To a greater extent than previously, these statistics thus contains a more complete count of the actual occurrences. These improvements were also enabled by a change by Statistics Norway in the processing procedures of the raw data. The disparities between previous years and the years from 2012 and onward are not of any great significance to the figures on prisoners per 1 January or the discharges. For the figures on new imprisonments and transfers made directly from custody to serving a prison sentence, and particularly with regard to the most severe crimes with a long processing time in the criminal justice system, there is a substantial break in the time series from the statistical year 2012.
As of 1 October 2015 there was a shift to a new sanction register SSP (3.0). All data for the statistical year of 2015 is collected from this register. The main units and variables are nevertheless approximately identical compared to previous years. As far as SSB is aware, the shift to a new sanction register has not resulted in considerable changes in the statistics on imprisonment completed by the Norwegian Correctional Service. However, arrests and custody imposed by the police was earlier a part of the collected data from the SSP. As of 1 October 2015 this type of data is not registered in the new sanction register, and is therefore no longer a part of the raw data which forms the basis for the statistics on imprisonment. As a result, the number of entries to custody and departures from custody by the shortest prison time might be slightly reduced compared to previous years.