Criminal Proceedings in Scotland, 2022-23

Annex B - Data quality, data processing and data confidentiality

Data quality: data processing system

B.1 The Criminal History System (CHS) is an administrative system used to track individuals through the criminal justice system and, as such, was not designed purely for statistical purposes. However, actions and processes have been put in place to ensure that Scottish Government statisticians understand the data. The data requirements for these extracts are contained in a joint specification document that has been agreed between Police Scotland and the Scottish Government.

B.2 Monthly extracts are uploaded onto a Scottish Government database at which point validation checks are undertaken to ensure a realistic number of records are added to the database. Checks are also made to ensure values for charges, court locations and disposal type are recognised. If any unexplained patterns or unrecognised codes are identified at the data upload stage, further investigations are undertaken. It may be necessary, at times, to go back to Police Scotland to verify the data.

B.3 Charge codes are the operational codes used to identify the crime or offence and are linked to legislation. New charge codes for crimes and offences under emerging legislation are created by the Crown Office and Procurator Fiscal Service (COPFS) on a monthly basis, and shared with the Scottish Government. When new codes are identified at the data upload stage they are verified and then added to a look-up table of recognised codes.

B.4 The Scottish Government is responsible for mapping each charge code to a crime code, which forms the basis of the crime code classification (see Annex D). There are around 8,300 charge codes which are mapped to around 600 crime codes, which in turn are (as of the 2021-22 publication onwards) grouped into 50 broader categories, and further into eight crime and offence groups. This mapping is agreed with individuals from Police Scotland and COPFS and enables consistent and comparable reporting between justice organisations.

Data quality: data processing system update

B.5 When we receive data from the CHS as described above, the monthly extracts mentioned in B.3 are processed into our local database. In preparation for the annual Criminal Proceedings publication, a process is run which collates the year’s data into a format that allows us to validate and analyse the information.

Data quality: validation of CHS data

B.6 Numerous data cleaning checks are performed and where issues have occurred these have been reported in the relevant bulletin. The last being in relation to 2018-19 data. These are then incorporated into future validation rules.

Data quality: data validation during production of the statistical bulletin

B.7 As a court proceeding or police/ COPFS non-court disposal can be made up of more than one offence, production of the statistics at ‘persons’ level requires an intermediary processing stage to be carried out on the CHS data. Where a person is proceeded against for more than one crime or offence in a single proceeding, only the main charge is counted. The main charge is the one receiving the most severe penalty (or disposal) if one or more charges are proved, and is identified using a look-up table which ranks the disposal types in order of severity.

B.8 For example, custody is ranked higher than a monetary fine, so for a proceeding where there was a mixture of these two types of disposal, the main charge counted for this record would be the charge associated with the custody disposal rather than the charge related to the monetary disposal.

B.9 If two charges have the same disposal, then the charge mapped to the lowest numbered crime code is taken as the main crime. Generally the lower the crime code, the more serious the crime would be considered to be. The lowest crime code is for murder and the highest for motor vehicle offences.

B.10 Once this dataset is created the following types of validation are carried out:

• Automated validation procedures and manual checks to identify any unrealistic data values e.g. long custodial sentences for petty crimes or short sentences for the most serious of crimes. Effort is also made to clean up records for which key information is missing e.g. missing court locations or age/sex of the offender. These are referred back to Police Scotland, Scottish Court and Tribunal Service (SCTS) or COPFS for correction or for explanation of any unusual circumstances.
• Other checks are carried out as necessary changes to the justice system. For example when new legislation is implemented, checks are undertaken to ensure cases are coming through the system at a realistic rate.
• Trends in the statistics are compared against case processing information published by COPFS and management information provided by SCTS to ensure that the volume of court proceedings are consistent. Information is compared by court type (e.g. high court, sheriff court etc.) to identify any differences.
• Further checks are undertaken by crime type, sentence type and other characteristics to identify any errors and unusual values. As an extra level of assurance, policy experts within the Scottish Government are consulted to identify why any significant changes may have occurred. Any relevant contextual information is then added to the bulletin.
• Similar consultation is undertaken with COPFS, SCTS and Police Scotland wherein results are shared purely for quality assurance purposes. Insight at an operational level provides invaluable feedback and informs whether further investigation of statistical quality is required.
• Further quality assurance and checking is undertaken on the statistics by members of Scottish Government Justice Analytical Services team.
• In recent years, we have carried out much more extensive quality assurance with external agencies. The purpose of this is to ensure the accuracy and quality of the statistics published. COPFS have identified that there may be a small number of court proceedings (often involving multiple charges and of a complex nature) which are being recorded as separate court cases which, in fact, should only be reported as one. The effect of this would be to over-estimate the true number of court proceedings. Investigations suggest that this affects all crime types, though to varying degrees.

Data confidentiality

B.11 Court proceedings are held in public and may be reported on by the media unless the court orders otherwise, for example where children are involved.

While our aim is for the statistics in this bulletin to be sufficiently detailed to allow a high level of practical utility, care has been taken to ensure that it is not possible to identify an individual or organisation and obtain any private information relating to them.

B.12 We have carried out a data protection impact assessment on our handling and use of personal data which is available along with a privacy notice.

B.13 We have assessed the risk of individuals being identified in the tables in this bulletin and have established that no private information can be identified. Where demographic information is provided, this is done either in wider categories of ages (for example tables 6, 21 and 22) or in numbers per 1,000 population (Table 5). This ensures that where there are small numbers, personal information about individuals cannot be identified.

B.14 Some of the additional data tables we provide alongside this publication have local authority information related to the offender. In the local authority tables, either demographic information is provided or offence-level information is provided, but not a combination of both. Similar to the main publication tables, demographic information is divided into wider age categories to further restrict the ability to identify individuals.

Revisions

B.15 The CHS is not designed for statistical purposes and is dependent on receiving timely information from Justice organisations. A pending case on the CHS should be updated in a timely manner but there are occasions when slight delays happen. Recording delays of this sort generally affect High Court disposals more than those of other types of court, as they are the most complex and lengthy trials. Also, the court may await reports before passing a sentence, so there may be a gap between when the defendant is found guilty and when a sentence is given. We only receive the data when the sentence details are given.

B.16 The figures given in this bulletin reflect the details of court proceedings as recorded on the CHS, that were concluded on or by 31 March 2023, and as provided to the Scottish Government up to the end of December 2023. Any subsequent updates on court disposals made will be incorporated into future bulletins and therefore some figures for 2022-23 (in particular those relating to the High Court) are likely to be subject to minor revisions.

B.17 These recording delays mean that figures for 2022-23 should be considered provisional as future bulletins may provide updates.

B.18 Records may be changed on the CHS, and these updates are included in the monthly data extracts that are sent to us. In some cases the sentence date may be changed due to changes in the sentence. This may move some of the sentences into the following financial year.

B.19 When revisions are required, they comply with the Scottish Government's policy on revisions and corrections.