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Prison Re-offending Estimates 2011-2017 Technical Note


A few key updates have been carried out on CSO estimates of prison re-offending rates for the reference years 2011 and onwards. Prisoner re-offending estimates are derived from matching Irish Prison Service data on released prisoners to An Garda Síochána’s PULSE system. The updates in the Prisoner Re-offending series are designed to:

  • Provide more clarity on re-offending by prisoner group (separating out prisoners who receive a custodial sentence from those whose sentence primarily consists of fines imposed by court). This is in line with what other jurisdictions do.
  • Provide a more up to date estimate of prison re-offending trends.
  • Improve the quality and consistency of prison re-offending data that is being used to calculate prison re-offending statistics.

This technical note provides details of the changes that have taken place. Tomorrow, 5 August, will see the publication of the updated Prisoner Re-offending series, bringing details of re-offending forward to reference year 2017. Revised data for 2011 and 2012 will be presented as well as estimates for 2014 - 2017 for the first time (in a few different measures).

Updates to the Prisoner Re-Offending series:

1. Custodial and Fine Sentence Court Outcomes

CSO have traditionally published prison re-offending estimates that include individuals released each year who had received either a custodial or fine sentence from the courts. The updated prison re-offending estimates from 2011 onward now separate these two types of sentences into different indicators. These are:

  • Prison re-offending – relating to individuals who have been released from a custodial reprimand.
  • Fine sentence re-offending – relating to individuals who have received a fine sentence order from court proceedings.

Fine sentences are court orders that only result in a custodial reprimand if a fine is not paid by the offender in the time that a judgement requires and, because most fines are paid when this outcome takes place, fine sentences do not generally result in a custodial period/detention. More than 96% of fine sentences do not involve a custodial period and, for those that do, it generally consists of only one or two days in custody.

Splitting the prison re-offending estimates into prison (custodial) and fine sentence (mostly non-custodial) re-offending, allows users to see more detail on the re-offending trends in Ireland.

2. Prison Release Years

Updates here relate to the use of the actual prison release date and not the original court release date. For statistical analysis purposes, this has resulted in the movement of a cohort of prisoners between years (if the year of their actual release was a different year to the court year), and has resulted in minor changes to the headline re-offending rate over time. 

3. The Addition of Supplementary Re-offending Indicators

Prison re-offending is calculated by matching an individual from the Prison Service releases dataset to a corresponding qualifying re-offence on An Garda Síochána PULSE system. From 2011 reference year onwards, CSO will also include an additional method of identifying a re-offence as well as the PULSE match. In cases when a released individual is replaced or re-committed back into custody within the relevant qualifying period, this will also be used as an indicator of re-offending. This update has had the following effect on the re-offending estimates:

  • Provided more consistency between PULSE and prison indicators of re-offending by including re-offenders who have been re-committed to prison when they may not be matched successfully to a PULSE identify. The number of such instances are small.

4. The Development of One-year Re-offending Indicators

CSO’s existing methodology of measuring prison re-offending sets three years as the period after a prison release for an individual to re-offend in order that the incident be included in the re-offending estimates. When an incident does take place in this three-year period, a further two-year limit is set for court proceedings relating to the incident to take place in order for it to qualify as being relevant. The two steps are designed to provide a comprehensive estimate of the identified re-offending rate. However, this method also means that there is a time lag for when CSO can provide re-offending estimates, with 2014 being the current most recent available year. To avoid such a data gap and provide more timely estimates of re-offending, CSO will, in addition to the three-year estimates, publish one-year re-offending estimates for custodial and fine sentence re-offending. The one-year estimates will include re-offences that have taken place within a year of release, with the period for a qualifying court outcome also being reduced to one year for this re-offending indicator. The reduced period of these re-offending indicators will allow estimates of re-offending to be published up to reference year 2017. Although one-year re-offending rates will not capture as many incidents as three-year re-offending rates, they will provide a more up to date indicator of the changing rates of re-offending over time.

5. Publication content

The forthcoming (5 August) Prisoner re-offending series will contain the following content:


1. Introduction - Key findings and overview 

2. Statistics under reservation - An explanation of CSO’s publications under reservation

3. Details of 3-year Custodial Re-offending - 3-year prison (custodial) re-offending rates classified by age, sex, offence type and re-offence type

4Details of 1-year Custodial Re-offending - 1-year prison (custodial) re-offending rates classified by age, sex, offence type and re-offence type

5. Details of 1-year Fine Sentence Re-offending - 1-year Fine sentence re-offending rates classified by age, sex, offence type and re-offence type

6. Historical Re-offending Indicators - Historical indicators of 3-year prison re-offending (Custodial and Fine sentence combined) classified by year

7. Frequently asked questions (FAQ’s) and Background notes - Methodological notes relating to prison re-offending calculations, FAQ’s, etc.

The CSO will continue to engage with users around all releases, and users can contact for further information or clarification in relation to the Prison re-offending publication if required.