Making sense of police statistics
July 18, 2009
On 10 July 2009 the Police released their 4th six-monthly report on Police activity since the statutory defence for assault on a child was removed from the Crimes Act 1961.
In an article printed in the New Zealand Herald [11 July] – “Big jump in child assaults reports” by Simon Collins claims that the number of minor assaults reported to the police has jumped 40% since the three month period before the law change. Taken at face value this could be interpreted as the 2007 law leading to a huge increase in the number of “good” parents being referred to the Police for correcting their children by simply smacking them. This is not the case.
To understand why, it’s important to knowhow the Police categorise the cases they report on. Police do not spell out the nature of the events involved in the cases they report but only say that, The terms “smacking”, “minor acts of physical discipline” and “other child assaults” are terms created for monitoring purposes so that the reviews accurately reflect the complex nature and context of each case. But in fact they represent a hierarchy with “other child assaults” being the heavier end of physical punishment.
By putting the categories together, looking at monthly averages and coming up with the 40% figure Simon creates a misleading impression.
If we use Simon’s average per month approach separately for each category we find that where “smacking” is concerned there is less than a 1% increase between the three month period before the law change and the figures reported in the last Police review. But in fact the numbers reported are so small that it is nonsense to talk percentages at all. About 1 case a month in the three month before law change and about 1.03 in the last review period is not a statistically significant change.
Looking at the “minor acts of physical discipline category” we find that there has been a 100% increase between the three month period before law reform and the last set of figures. But in fact we are talking about the difference between say 3 cases a month and 6 cases a month – again too small a number to be meaningful.
In the third category “Other Child Assault” we are looking at a rise from about 27 cases a month to 34 cases a month in the relevant periods – a little over 25% increase – but again 7 cases is not a statistically significant change.
The slight increase in reporting at the heavier ends of physical punishment should be interpreted positively – as demonstrating a greater willingness on the part of the public to report concerns about the way a child is treated – and as making more opportunities for parents to be given support and guidance to manage their children’s behaviour in more positive ways.
The case of the Christchurch ‘ear-flick’ Dad who apparently punched his child on the face and was given an anger management sentence illustrates the point.
We must also keep in mind that the total number of prosecutions in the “smacking” and minor acts of physical discipline categories has been vey small over the whole period.
