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Measuring success – key performance indicators for forces

How the police service assesses its current provision of specialist investigation of rape.

First published

Why we measure performance

Measuring the performance of police forces in rape and serious sexual offences (RASSO) investigations is crucial. It allows for continuous improvement, ensuring procedural fairness for all individuals involved.

Each force needs to understand their capability and the requirements necessary to improve. Forces have a responsibility to improve the capability and wellbeing of investigators.

The aims and principles of the national operating model translate into specific objectives that show what good looks like for:

  • RASSO investigators
  • investigations
  • engagement with victims
  • force corporate support

Key performance indicators

The KPIs and mechanisms to review police practices in this guidance are examples of ways of measuring how police forces are improving. 

They will assist forces in continuous and iterative improvement. Forces are not expected to assess themselves against every KPI or mechanism listed. Most forces do not yet have the data and analytic capability to do so. However, forces should aim to be transparent and collaborative with continuous improvement and independent oversight to ensure legitimacy.

Forces can gain a complete view by making sure that they track at least some indicators from each of the aims and principles. They should not concentrate improvement in some areas (for example, solely focusing on increasing charge volumes) at the expense of the health and sustainability of RASSO work (for example, victim wishes, but also officer workloads, burnout or continuous learning and development). Success rests on a whole system improvement.


Aim one – outcome justice for all victims


  • Increase charge volumes where victim wishes a prosecution.
  • Reduce disparity in charge volumes between victims of different protected characteristics (for example, race, sex and sexual orientation).

KPIs and assurance mechanism

  • Monitor charge volumes for victims by protected characteristics.

Aim two – procedural justice for all victims and all suspects


  • Demonstrably improve police procedural fairness for victims of all backgrounds.
  • Uphold victims’ rights and provide minimum service standards consistent with the Victims’ Code of Practice.

KPIs and assurance mechanism

Aim three – reduction and prevention of RASSO


  • Routine and reliable identification of repeat suspects.
  • Stopping known perpetrators from offending again.

KPIs and assurance mechanism

  • Monitor the proportion of named RASSO suspects who are repeat suspects.



Specialist knowledge of sexual offending behaviour and its impact on victims informs RASSO investigations and offence prevention. Within it, officers are bound to act consistently with the human rights of suspects and victims, as enshrined in the European Convention on Human Rights (ECHR) and incorporated into domestic law by the Human Rights Act (HRA) 1998.


  • Application of a suspect-focused approach to investigations.
  • Officers applying specialist knowledge of serious sexual offending behaviour in investigations.
  • Good quality investigations and file preparation.

KPIs and assurance mechanism

  • Yearly case file review evidence methodology and transparent discussion with local criminal justice board and police and crime commissioners on results.


Procedural justice principles underpin all officer interactions with victims. Victim rights and needs inform officer decision-making in RASSO investigations.


  • Providing victims with information about their case.
  • Empowering victims to make informed decisions within the investigation process.
  • Treating victims with dignity and respect.
  • Respecting victims’ rights as protected by the European Convention on Human Rights (ECHR), HRA and the Data Protection Act 2018.
  • Adhering to the Victims’ Code of Practice.

KPIs and assurance mechanism


Officers take the context of the offence into consideration from the moment the offence is disclosed to police. This includes the:

  • victim-suspect relationship context
  • victim context, including whether they want an investigation
  • suspect context, uncovered through a suspect-focused investigation


  • Reduced disparity in outcome and procedural justice for victims and suspects across the victim-suspect relationship contexts and the victim context, including whether they want an investigation
  • Greater focus on the suspect context for offending, uncovered through a suspect-focused investigation.

KPIs and assurance mechanism

  • Monitor charge volumes across relationship contexts and protected characteristics.
  • Publish results from the police experience survey for victims of RASSO conducted by City, University of London as part of Operation Soteria, which breaks down findings by relationship context.

In-force organisational improvement principles

Resourcing in line with RASSO demand and the strategic policing requirement


  • Reliable and up-to-date figures on RASSO demand and per-officer case load.
  • Achieve optimum officer workload.

KPIs and assurance mechanism

Organisational justice for officers, including a commitment to staff care and continuous learning and development


  • Reduction in RASSO officer sick leave and burnout.
  • Routine use of reflective practice.
  • Increase in meaningful supervision.
  • Increase the number of officers with completed accreditations and continuing professional development courses.

KPIs and assurance mechanism

Meaningful collection, analysis and interpretation of police performance and administrative data to inform operational planning and strategic decision-making


  • Improve completeness and quality of police recorded data.
  • Yearly review of capacity and capability of force analysts to support operational and strategic RASSO decision making.
  • Correct application of appropriate outcome codes.
  • Improve understanding of reasons for crime outcome finalisation using subcodes.

KPIs and assurance mechanism

  • Problem profile.
  • Percentage of missing data by protected characteristics.
  • Percentage of missing data on relationship context of recorded RASSO.
  • Yearly review of appropriate use of crime outcome codes and subcodes by an independent panel.

Digital forensic capability and competence to enable a suspect-focused, victim-centred and context-led approach to digital forensic evidentiary material


  • Digital data-trained ‘capable’ RASSO officers.
  • Proportionate, evidence-driven, digital investigative strategies for all RASSO cases involving digital data.
  • Appropriate analysis of digital data.

KPIs and assurance mechanism

  • Yearly review of digital capability within RASSO units (to include a review of the training provided and undertaken).
  • Dip-sample six-monthly review of digital processing notices (DPNa and DPNc) forms completed by digital forensic unit (DFU) staff and operational officers.
  • Dip-sample six-monthly review of digital strategies.
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