## How The Measure Of Proven Re-Offending Has Changed And The Effect Of These Changes Ministry Of Justice Statistics Bulletin

 

## How The Measure Of Proven Re-Offending Has Changed And The Effect Of These Changes

 Background The MoJ launched a statistical consultation on improvements to the transparency and accessibility of our information in 2010 and a response to the consultation was published in March 20111. One aspect of the consultation was the measurement of proven re-offending. Prior to the consultation there were six different measures of proven reoffending: 

 National adult proven re-offending; 
 
 Local adult proven re-offending; 
 
 National youth proven re-offending; 
 
 Local youth proven re-offending; 
 
 Prolific and other priority offending (PPO); and 
 
 Drug-misusing proven offending. The new approach to measuring proven re-offending integrates these 
approaches into a single framework. This allows users to: 
 form a clear picture of proven re-offending at national and local levels; 
 
 compare adult and youth results, and enable other work on transition 
between the youth and adult criminal justice systems; 
 
 understand how results for different offender groups (such as those 
managed by the prison and probation services, those under the PPO 
schemes, drug-misusing offenders, first time entrants, etc.) fit in to the 
overall picture on proven re-offending; and 
 
 continue to analyse proven re-offending behaviour for particular types 
of offender. 
 
Comparing trends in re-offending Table 1 shows the proportion of offenders with a proven re-offence/reconviction using the new measure of re-offending and the previous measures of adult re-conviction and juvenile re-offending. Comparisons we make use cohorts up to 2009. Re-offending rates are lower using the new measure than using the previous measure. The differences are as follows: 

 For adult and juvenile offenders the new measure is based on all 
offenders released from custody, receiving a non-custodial conviction 
at court, a caution, reprimand, warning or tested positive for opiates or cocaine over a 12 month period, but the previous measures only 
included offenders released from custody or commencing a court order in the first three months of the year. Using a three month sample overrepresents prolific offenders in comparison to a full year's worth of data. 
 
 For adults the new measure counts all offenders including those who 
received a caution, fine or discharge, where the previous adult measure only included those who commenced a court order or who were discharged from custody. 
 
 For adult offenders, the new measure is a measure of proven reoffending (which counts offences proven through a court conviction or a caution) whereas the previous measure is a measure of re-conviction (which only counts offences proven through a court conviction). 
 As a result, re-offending rates are 14.4 percentage points lower for adults and rates for juveniles are 4.1 percentage points lower using the new measure. However, the re-offending rates are similar for adults given a court order or who received a custodial sentence, including those given a sentence of less than 12 months. Rates are between 1.0 and 2.6 percentage points lower using the new measure. Table 1: Re-offending using the new and previous measures, 2009 

|                                                    |   New measure  |   Previous measure(s) |
|----------------------------------------------------|----------------|-----------------------|
| Adults                                             |           24.9 |                  39.3 |
| Juveniles                                          |           32.8 |                  36.9 |
| Adults given a court order                         |           34.5 |                  35.5 |
| Adults given a custodial sentence                  |           46.8 |                  48.5 |
| Adults given a custodial sentence of less than 12m |           56.8 |                  59.4 |
|                                                    |                |                       |

 Figure B1 shows re-offending rates for adult offenders between 2000 and 2009 using the new and previous measure. For 2009, 24.9% of adult offenders have a proven re-offence within 12 months using the new measure compared to 39.3% using the previous re-conviction measure. However, trends for adult offenders are similar using the two measures. The proportion of offenders with a proven re-offence/re-conviction rose between 2000 and 2002, fell between 2002 and 2006, rose between 2006 and 2008, and fell between 2008 and 2009 using both measures. 

The overall reduction in re-offending is smaller using the new measure (1.2 percentage points between 2000 and 2009 and 0.5 percentage points between 2008 and 2009) than using the previous measure (3.7 percentage points between 2000 and 2009 and 0.8 percentage points between 2008 and 
2009). In 2009, 32.8% of young offenders re-offended within 12 months using the new measure compared to 36.9% using the previous measure. The reduction in re-offending is smaller using the new measure (0.9 percentage points between 2000 and 2009 and 0.1 percentage points between 2008 and 2009) 
than using the previous measure (3.3 percentage points between 2000 and 
2009 and 0.4 percentage points between 2008 and 2009). Overall, the trends are broadly similar. Trends in proven re-offending/re-conviction rates for adult custodial offenders are similar using the new and previous measures. The proportion of offenders given a custodial sentence of less than 12 months who re-offended rose between 2000 and 2009 using both measures (by 2.6 percentage points using the new measure and 1.4 percentage points using the previous measure). The proportion of offenders given any custodial sentence who re-offended fell between 2000 and 2009 using both measures (by 2.6 percentage points using the new measure and 2.9 percentage points using the previous measure). 

## 

 The change in methodology The following sections provide detail regarding the change in methodology between the methods in measuring re-offending and how those changes impact on the data. The table below provides a comparison of the previous methodologies with the new approach.

## 

Comparison of previous and new measures of proven re-offending 
 
Previous measures of re-offending 
New measure of reoffending 
 
National adult 
re-conviction 
Local adult reoffending 
National youth reoffending 
The cohort 
Offenders aged 18+ discharged from custody or commencing court orders under probation 
supervision between January to March 
Offenders aged 18+ on the probation caseload at the end of each calendar quarter 
Offenders aged 10- 17 discharged from custody, receiving a court conviction or receiving a caution/reprimand or 
final warning between January and March 
The follow-up period to measure reoffending 
12 months for offences to occur and a further 6 months for offences to be proved 
3 months for offences to occur and a further 3 months for offences to be proved 
12 months for offences to occur and a further 6 months for offences to be proved 
Local youth reoffending 
Prolific and other Priority Offending (PPO) 
Drug-misusing offending 
Offenders aged 10-17 discharged from custody, receiving a court conviction or receiving a caution/reprimand 
or final warning between January and March 
All offenders identified as being on the PPO scheme as at 1 April 
All Class A drug offenders identified through positive drug tests on arrest, OASyS 
or drug requirement as part of a court order, CJIT identification, or identification on prison release between January and March 
All offenders who received a caution/reprimand or warning, were convicted at court (other than custody), 
were discharged from custody, or tested positive for cocaine or opiates on arrest over a 12 month period. 
12 months for offences to occur and a further 3 months for offences to be proved 
12 months for offences to occur and a further 3 months for offences to be proved 
12 months for offences to occur and a further 3 months for offences to be proved 
12 months for offences to occur and a further 6 months for offences to be proved 
Comparison of previous and new measures of proven re-offending 
Previous measures of re-offending 
New measure of reoffending 
 
Local adult reoffending 
National youth reoffending 
Local youth reoffending 
Drug-misusing offending 
National adult re-conviction 
The headline measure 
Frequency of reoffending (the number of proven re-offences per 100 offenders) 
Proportion of offenders reoffending, compared to the rate that would be expected based on the offender characteristics 
Frequency of reoffending (the number of proven reoffences per 100 offenders) 
What counts as a proven reoffence 
Offences committed within the follow-up period which were proved by a court conviction either within the follow-up period or in a further six months 
Offences committed within the follow-up period which were proved by a court conviction or caution either within the follow-up period or in a further three months 
Offences committed within the follow-up period which were proved by a court conviction or reprimand or final warning either within the follow-up period or in a further six months 
Prolific and other Priority Offending 
(PPO) 
Frequency of reoffending (the number of proven re-offences per 100 offenders) 
Number of further offences compared to number in previous year, against the reduction that would be expected given time on the PPO scheme 
Number of further offences compared to what would be expected based on their previous offending history 
Proportion of offenders reoffending We also include information on the frequency of reoffending and information on the predicted rate based on offender 
characteristics 
Offences committed within the follow-up period which were proved by a court conviction or reprimand or final warning either within the follow-up period or in a further three months 
Offences committed within the follow-up period which were proved by a court conviction or caution either within the follow-up period or in a further three months. Breach offences that lead to substantive recorded convictions are included 
Offences committed within the follow-up period which were proved by a court conviction either within the follow-up period or in a further three months 
Offences committed within the follow-up period which were proved by a court conviction or caution/reprimand or warning either within the follow-up period or in a further six months 
Comparison of previous and new measures of proven re-offending 
Previous measures of re-offending 
New measure of reoffending 
 
Local adult reoffending 
National youth reoffending 
Local youth reoffending 
Drug-misusing offending 
National adult re-conviction 
Prolific and other Priority Offending 
(PPO) 
Use of a predicted rate 
A predicted rate of re-offending was included for the proportion of offenders expected to reoffend based on their characteristics 
A predicted rate of re-offending was included for the proportion of offenders expected to reoffend based on their characteristics 
A predicted rate of re-offending was included for the proportion of offenders expected to re-offend based on their characteristics 
No predicted rate 
Evidence on the 
link between time on the PPO scheme and expected reductions in further offending were used to assess reductions in number of 
offences compared to the previous year
A predicted rate of re-offending was included for the proportion of offenders expected to reoffend based on their previous criminal history 
A predicted rate of re-offending is included for the proportion of offenders expected to re-offend based on their characteristics 
 
Logistic regression is used 
Response 
surface methodology was used 
Logistic regression was used 
Logistic regression was used 
Logistic regression was used 
Data source 
Police National Computer 
Police National Computer 
Police National Computer 
Youth Offending Teams data 
Police National Computer 
Police National Computer 
Police National Computer 
Geographic breakdown 
None 
Region, 
Probation area, Local Authority 
None 
Youth Offending 
Team level 
Police Force and Local Authority level 
Drug Action team and Local Authority level 
Upper and lower tier local authority areas for all offenders. Other breakdowns for specific categories of offender. 

## The Effect Of The Changes Adults Differences In Methodology Are Reflected In Different Results. Table 3 Shows The Impact On Reported Rates Of Adult Re-Conviction/Re-Offending. The Table Breaks Down The Changes Between The Previous Measure And The New Measure To Identify The Different Effects Of The Changes In Methodology.

Previous1 measure: reconvictions (prison and 
probation offenders only), 
first quarter of the year
Previous measure: reconvictions (prison and 
probation offenders only), 
whole year
New measure: reoffending (prison and 
probation offenders only), 
whole year
New measure: proven reoffending (all offenders), 
whole year
Proportion 
2000
43.0
40.0
40.9
26.2
2002
45.5
42.0
43.0
27.6
2003
45.4
41.5
42.4
26.9
2004
42.9
38.6
39.8
25.5
2005
41.2
36.6
38.4
24.9
2006
38.6
35.6
37.6
24.6
2007
39.0
35.9
37.9
24.8
2008
40.1
36.1
37.9
25.4
2009
39.3
34.7
36.2
24.9
Frequency (average per offender)
2000
1.85
1.66
1.69
0.89
2002
2.13
1.84
1.87
0.99
2003
2.05
1.73
1.76
0.93
2004
1.81
1.51
1.54
0.83
2005
1.66
1.36
1.40
0.77
2006
1.44
1.26
1.31
0.73
2007
1.47
1.27
1.32
0.73
2008
1.55
1.27
1.31
0.75
2009
1.41
1.15
1.18
0.70
Frequency of re-offenders (average per re-offender)
2000
4.30
4.15
4.13
3.39
2002
4.68
4.39
4.36
3.59
2003
4.52
4.18
4.15
3.44
2004
4.23
3.91
3.87
3.27
2005
4.03
3.70
3.65
3.10
2006
3.73
3.54
3.48
2.95
2007
3.78
3.53
3.48
2.94
2008
3.88
3.51
3.46
2.93
2009
3.57
3.31
3.27
2.80
Number of offenders
2000
42,734
148,052
148,052
477,698
2002
43,247
157,243
157,243
495,664
2003
44,095
159,686
159,686
520,660
2004
46,532
163,775
163,775
512,600
2005
43,429
170,021
170,021
532,045
2006
50,281
181,726
181,726
571,458
2007
50,085
190,418
190,418
595,020
2008
53,718
197,035
197,035
589,948
2009
56,616
200,077
200,077
576,255

1. Based on the national adult re-convictions publication (March 2011) Among adult offenders in 2009, the previous national measure (the first column) shows that 39.3% of adult offenders were re-convicted within a year based on a sample of 56,616 offenders. 

The second column shows the re-conviction rates from the previous measure looking at offenders who were released from custody or commenced a court order, but at any point during the year. The inclusion of offenders from a full 12 month period means the results are calculated using the full proven offender population rather than a sample - this ensures we do not overrepresent prolific offenders in the cohort, which is a problem in using a January to March sample as in the previous adult re-conviction measure. This leads to a lower proportion of re-convicted offenders (between three and five percentage points, e.g. 34.7% compared to 39.3% in 2009). The change to a full year also increases the number of offenders, to 200,077 in 20092. The third column shows the proven re-offending rates from the new measure, but still based only on those offenders who were released from custody or commenced a court order at any point during the year. Proven re-offending includes offences which result in a caution in addition to those resulting in a conviction at court. The proportion of offenders who were proven to re-offend is between one and two percentage points higher than for those who were reconvicted (36.2% compared to 34.7% in 2009). There is little difference at this stage because we are still only considering offenders who already have a prison or a court order. The fourth column shows the re-offending rates from the new measure looking at all adult offenders who received a caution, a conviction at court, discharged from custody, or tested positive for cocaine or opiates. The inclusion of these offenders increases the numbers considerably. In 2009, the previous adult measure tracks the re-offending behaviour of 56,616 offenders; 
the new measure tracks 576,255 offenders. The inclusion of offenders who received less severe disposals and are generally less prolific in nature reduces the proportion who re-offend by around 11 to 16 percentage points 
(36.2% compared to 24.9% in 2009). Change over time Compared to the previous measure, the reduction over time in the proportion of offenders who re-offend is much lower using the new measure. Using the previous measure, between 2000 and 2009, the proportion of offenders who were re-convicted fell 3.7 percentage points (from 43.0 to 39.3%). Using the new measure, the proportion of offenders who committed a proven re-offence fell 1.2 percentage points (from 26.2 to 24.9%). 

Juveniles The only change between the previous measure and the new measure of reoffending among young people is the move from a one quarter sample to including all young offenders over the period of a year. 

Previous measure1             

proven re-offending
New measure proven reoffending 
Proportion 
2000
40.2
33.7
2002
38.5
33.4
2003
39.0
34.3
2004
38.6
33.6
2005
38.4
33.6
2006
38.7
33.9
2007
37.5
32.5
2008
37.3
32.9
2009
36.9
32.8
Frequency (average per offender)
2000
1.51
1.12
2002
1.42
1.10
2003
1.42
1.09
2004
1.32
1.03
2005
1.25
0.98
2006
1.23
0.97
2007
1.16
0.90
2008
1.14
0.91
2009
1.10
0.90
Frequency of re-offenders (average per re-offender)
2000
3.77
3.32
2002
3.69
3.29
2003
3.63
3.19
2004
3.43
3.06
2005
3.26
2.91
2006
3.18
2.86
2007
3.08
2.77
2008
3.06
2.75
2009
2.99
2.75
Number of offenders
2000
41,176
139,326
2002
40,753
136,401
2003
40,297
138,379
2004
44,153
149,452
2005
45,337
163,545
2006
48,938
171,061
2007
52,544
171,454
2008
44,837
145,579
2009
37,472
121,107

1. Based on the national juvenile re-offending publication (March 2011) publication As for adults, using the whole year reduces the proportion of offenders who re-offended because we do not over-represent prolific offenders in the cohort, which is a problem in using a January to March sample. Table 4 shows the reduction is between four and seven percentage points. For 2009, with the previous measure, 36.9% commit a proven re-offence within one year; with the new measure, 32.8% do so. The new measure, which is based on offenders from a 12 month period, includes over three times as many offenders as the existing measure. Change over time Compared to the previous measure, the reduction in the proportion of offenders who re-offend between 2000 and 2009 is much lower using the new measure. 

Using the previous measure, between 2000 and 2009, the proportion of offenders who were proven to re-offend fell 3.3 percentage points (from 40.2 to 36.9%). Using the new measure, the proportion of offenders who committed a proven re-offence fell 0.9 percentage points (from 33.7 to 32.8%). 

 
Drug-misusing offenders Published results for drug-misusing offenders on the previous measure covered 2008 and 2009; results using the new measure cover from 2004 onwards. The previous measure: 

 Includes offenders who have been identified in the first quarter of the 
year, whereas the new measure includes offenders from any point during the year. 
 
 Includes all drug-misusing offenders irrespective of the date of proven 
offence, whereas the new measure includes identified drug-misusing 
offenders who have received a caution, been convicted at court, been discharged from custody, or tested positive for cocaine or opiates on 
arrest during a 12 month period. 
 
 Counts re-offences that were proven through a court conviction, 
whereas the new measure counts re-offences that were proven by a court conviction or caution. 
 As for adult and juvenile offenders, using the whole year to identify offenders reduces the proportion of offenders who re-offend, because we do not overrepresent prolific offenders in the cohort, which is a problem in using a January to March sample. Table 5 shows the impact on reported rates of reoffending/re-conviction by drug-misusing offenders. 

## 

Previous measure1 proven reconviction
New measure of proven reoffending 
Proportion 
2004
67.3
2005
65.3
2006
58.6
2007
57.2
2008
61.0
56.4
2009
57.0
54.7
Frequency (average per offender)
2004
3.20
2005
2.94
2006
2.37
2007
2.34
2008
2.6
2.29
2009
2.2
2.10
Frequency of re-offenders (average per re-offender)
2004
4.75
2005
4.51
2006
4.03
2007
4.09
2008
4.3
4.06
2009
3.9
3.84
Number of offenders
2004
20,652
2005
29,112
2006
44,597
2007
54,474
2008
20,934
59,039
2009
20,109
53,109

1. Based on the national drug-misusing offenders publication (December 2010) Table 5 shows that the proportion of offenders who commit a proven reoffence is between two and five percentage points lower using the new measure (57.0% using the previous measure compared to 54.7% using the new measure). The new measure, which follows offenders over a 12 month period, includes between two and three times as many offenders as the existing measure. 

Prolific and other priority offenders Published results for prolific and other priority offenders (PPOs) on the previous measure presented the frequency of proven re-offending for all PPOs; results using the new measure cover the proportion of offenders proven to re-offend, and the frequency of proven re-offending for all offenders and for re-offenders from 2005 onwards. 

The previous measure: 

 Includes offenders who have been identified in the first quarter of the 
year, whereas the new measure includes offenders from any point 
during the year. However, PPOs are generally on the PPO programme 
for a sustained period of time so this only has a moderate impact on numbers of offenders included. 
 
 Includes all identified PPOs, whereas the new measure includes 
identified PPOs who have tested positive for cocaine or opiates, 
received a caution, been convicted at court, or been discharged from 
custody during a 12 month period. 
 
 Counts re-offences that are proven through a court conviction or 
caution and also includes breach offences that lead to substantive recorded convictions. The new measure only includes re-offences proven through a court conviction or caution. 

## Table 6 Shows The Impact On Reported Rates Of Proven Re-Offending By Ppos And On Numbers Of Offenders Included In The Measure.

Previous  measure1 proven reoffending
New measure of proven reoffending 
Proportion 
2005
77.0
2006
75.7
2007
75.8
2008
77.2
2009
56.0
75.1
Frequency (average per offender)
2005
4.01
2006
3.83
2007
3.80
2008
2.6
3.80
2009
2.4
3.49
Frequency of re-offenders (average per re-offender)
2005
5.21
2006
5.06
2007
5.01
2008
4.93
2009
4.3
4.65
Number of offenders
2005
8,555
2006
8,239
2007
8,309
2008
10,771
8,607
2009
10,635
8,156
1. Based on the national Prolific and other Priority Offenders publication (March 2010)

 
The average number of proven re-offences committed by PPOs in 2009 is lower for the previous measure than for the new measure in 2008 (2.4 reoffences per offender using the previous measure, but 3.49 using the new). The previous measure includes PPOs who have not been proven guilty of an offence or been discharged from custody in the 12 month period when the reoffending cohort is formed. This type of offender is likely to have a lower level of re-offending. These differences may help to explain: 

 why the frequency of re-offending is lower for the previous measure 
than for the new measure in 2009 (2.4 re-offences per offender using the previous measure, but 3.49 using the new); and 
 
 why the previous measure includes nearly 2,500 more PPOs in 2009 
than does the new measure. 

## Local Adult Re-Offending The Most Similar Results For The New Measure Of Re-Offending And The Existing Local Measure Of Adult Re-Offending Are The Early Estimates Of Re-Offending Of Offenders Given A Court Order. Like The Existing Measure Of Local Adult Reoffending, The Early Estimates Of Offenders Given A Court Order:

 measure re-offending over three months; 
 
 only measures offenders under probation supervision; 
 
 provides results by probation trust; and 
 
 compares actual re-offending rates with a predicted re-offending rate. 
 There remain significant differences between the early estimates and the existing local adult measure of re-offending, including: 

 The existing local adult measure includes offenders on licence - the 
early estimates include offenders commencing court orders only; 
 
 The existing local adult measure uses a 'snapshot' approach. This 
means offenders are counted if they are on the caseload at certain times in the year. Offenders who are on the caseload for a short period 
of time may not get counted with the existing measure. The early 
estimates count every offender who commences a court order; 
 
 Because the existing local adult measure uses a 'snapshot' approach 
some offenders may get counted up to four times if they are on the 
caseload for over 12 months. The early estimates count every offender once; 
 The existing local adult measure measures the re-offending of 
offenders at any point during the court order - the early estimates 
measure re-offending in the first three months after an offender 
commenced a court order; and 
 
 The predicted score for the existing local adult measure was derived 
from analysis of 2007 re-offending data and the prediction for the early estimates was derived from analysis of 2008 re-offending data. 
 These differences explain why the re-offending rate is higher with the early estimates of re-offending by offenders commencing a court order than with the existing measure of local adult re-offending: 

 offenders on licence have lower rates of re-offending than those 
commencing a court order; and 
 
 offenders serving a court order have lower rates of re-offending the 
longer they are on that court order. 
 However, the prediction for the early estimates has been tailored specifically to the relevant group of offenders. Local youth re-offending The previous measure of youth re-offending used data that Youth Offending Teams (YOT) collected themselves from their local police and courts. The measure was used as management information and was never published or put into the public domain. The new measure uses data from the Police National Computer (PNC). Internal analysis and discussion with stakeholders has highlighted a number of differences between the two data sources: 

 The PNC includes a number of offenders who have received a 
reprimand or final warning which do not always appear on the YOT 
systems. As a result, there are more youth offenders and a higher overall youth re-offending rate using the new measure than using the previous local youth re-offending measure. 
 
 The PNC includes more comprehensive data on re-offending as adults 
by offenders who originally offended as youths. 
 
 Using PNC data reduces the data-collection burden on YOT and local 
police forces. 
 
 PNC data measures re-offending on recordable offences and YOT data 
measures re-offending on all offences. Offences which are not recordable include speeding offences, parking offences and other minor motoring offences. As a result, YOT data is more comprehensive for motoring re-offences. 
 
 
 The new measure allocates offenders to a locality using their home 
address data from the PNC; the previous local youth measure allocated offenders using offender management data. As a result, Looked After Children (LAC) who are in foster care, or in a children's 
home, or in a boarding school or live with another adult known to children's services, maybe allocated to a different YOT under the previous youth measure than the new measure. 
 
 For their re-offending to be included in the new measure, administrative 
data on young people in custody and secure accommodation has to be 
matched to the PNC. Some cases are not successfully matched. This 
process was not required for these offenders to be included in the previous local youth measure. As a result, YOT data can be more comprehensive regarding custodial offenders or those in secure accommodation. 
 
 Using PNC data provides an external measure of youth re-offending, 
which makes it an appropriate data-source to support any future 
policies which tie local funding to re-offending performance. 
 
 Using PNC data allows local youth re-offending to be measured on the 
same basis as national youth re-offending and adult re-offending, permitting adult and youth re-offending to be measured on a like-forlike basis and a more comprehensive picture of re-offending to be 
formed. Work is underway to fully quantify the extent of these differences. 

## Contact Points

Press enquiries should be directed to the Ministry of Justice press office: Tel: 020 3334 3536 
Email: newsdesk@justice.gsi.gov.uk Other enquiries about these statistics should be directed to: Mike Elkins Ministry of Justice Justice Statistics Analytical Services 7th Floor 102 Petty France London SW1H 9AJ Tel: 020 3334 2946 General enquiries about the statistical work of the Ministry of Justice can be emailed to: statistics.enquiries@justice.gsi.gov.uk General information about the official statistics system of the United Kingdom is available from www.statistics.gov.uk.