Corrections cuts crime with the selective use of statistics

In July 2014 the NZ Herald revealed the police have been cooking the crime stats in Papakura. Now The Daily Blog is asking the question: Has the Government manipulated Corrections statistics as well? The answer is yes.  But this is not being done by a few rogue Corrections officers. This is a systemic practice conducted in Corrections head office.

The Department claims it is focused on reducing reoffending and the diagram below taken from its website suggests that in April 2013, re-offending was down by 9.3% over the previous two years. The Department says it is on target to reduce reoffending by 25% by 2017.
When the government announced the goal of 25%, they said: “This will mean 600 fewer prisoners re-imprisoned one year after release, and 4,000 fewer offenders reconvicted within a year of beginning their community-based sentence.”

But the latest Corrections report (2013) on Trends in the Offender Population, effectively contradicts most of the Government’s claims about reduced reoffending.

Prison numbers

The report shows there has been no drop whatsoever in the number of people in prison (see graph).  In fact the number of sentenced prisoners has gone up dramatically – by 166% since 1983.Prison numbers

The best that Corrections could claim about this graph was that “From 2010 there has been a flattening in the sentenced prisoner population.”

Looking at it more closely reveals that the rate of increase also ‘flattened’ between 1983 and 1987; between 1992 and 1995; and between 1999 and 2003. After each of these ‘flatlines’, the muster continued its inexorable rise.

Offenders in the community

In regard to offenders on community-based sentences, the increase has been even more dramatic. The report says: “The number of offenders starting a new community sentence during 1983 was 14,407. This increased by 219 percent, to 48,379, in 2010.”  As with prison numbers, the overall trend is up, not down.Community numbers

But Corrections claims that: “The number of offenders starting a community sentence each year has decreased markedly since 2010. Between December 2011 and December 2013, re-offending has reduced, equating to 11.7% progress towards the target of reduced re-offending by 25 percent by 2017.” (See graph)

Sure, there has been a small drop in the last two years, but it is far too soon to determine whether this is anything other than a temporary dip in the upward trend. The report shows there was a similar drop between 1994 and 2000 – followed by a rapid rise to a new peak in 2010. Corrections’ exaggerated claims about the dip in the last two years are premature; they ignore the long-term upward trend in which the dip may be just a natural variation.

Selective statistics

In fact the dip is not natural. It’s entirely manufactured – by the selective use of flawed statistics.  To make it look like reoffending (by those on community based sentences) is down, Corrections only includes statistics of those who reoffend within 12 months from the start of their sentence, rather than within 12 months from the end of their sentence.  That’s ridiculous.  It’s like measuring the reoffending rate of prisoners while they are still in prison, with almost no capacity to commit further crime. No wonder the reoffending stats are down.

A more useful analogy is to compare reoffending rates with the survival rate of cancer victims. Measuring  survival from the start of chemotherapy or radiation treatment would not tell us much.  It’s only after treatment is complete, assuming the patient survives, that its effectiveness can be evaluated. This is done by measuring survival rates five or even ten years later. 

Short term snapshots

The same applies to criminal reoffending.  The reality that the longer a recidivist offender is at large in the community, the greater the chance he will eventually reoffend. A more detailed analysis conducted by Corrections (Reconviction patterns of released prisoners: A 60-months follow-up analysis) shows that approximately 26% of prisoners reoffend and are re-imprisoned within 12 months of release. But after five years – 52% are back in prison.  In other words, approximately half of all ex-prisoners who subsequently reoffend manage to survive in the community for more than 12 months before they commit another crime and go back to prison. But Corrections is not counting these crimes.

What this means is that the statistical data that Corrections is using to prove it’s on track towards the 25% goal comes from short term snapshots and is therefore incomplete and misleading.  For those on community based sentences the snapshot is so short, it begins at the start of the sentence while the offender may still be on home detention. This is a cynical and deceptive use of statistics which fails to provide an accurate or realistic picture of criminal behaviour in New Zealand.

2 thoughts on “Corrections cuts crime with the selective use of statistics

  1. I believe this too. Ive been informally told by a police officer that if there is no sure suspect and evidence is slight, then the officers may not wish to record an incident, even though a member of the public had reported it, for instance a burglary.


  2. Most criminologists would agree that the measurement period for reoffending should be 5 years, not 12 months. There was a certain special focus unit in a certain North Island prison which was closed because the Dept claimed they couldn’t reliably measure its success rate with respect to reoffending. But now, lo and behold, the Dept can measure their own “success” rate as little as 3 months later.


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