web analytics

Statistical crimes and the media

Written By: - Date published: 1:44 pm, April 11th, 2009 - 8 comments
Categories: crime, Media - Tags:

You might have noticed that there was none of the traditional beat-up over crime when the crime statistics came out last week even though reported crime was up 1.2%. The reason is pretty obvious. The right is on power now, so National, the Sensible Sentencing Trust, and the Herald have no interest in trying to generate public fear of crime and with it anti-government feeling.

Nonetheless, it did provide an opportunity for some journalists to display their problems with basic statistics. Take this mess from Stuff and NZPA:

“Violent crime in New Zealand continues to rise, largely driven by increasing family violence.

Across the region there were 1,200 less crimes in total recorded. That means every day last year three less people were affected by crime than in 2007.

Auckland City recorded the biggest decrease in total crime with four per cent fewer offences last year

One in every 10 Aucklanders is likely to experience a crime of some sort most of those unlucky ones being victims of burglary….

…just 760 people in every 10,000 being hit by crime”

Of course, it should read “1,200 fewer crimes” but the innumeracy is worse than the literacy.

Not all crimes that happen are recorded. So an increase in the number of recorded violent offences does not necessarily mean the number of actual violent offences increased. All the journalists had to do was add the word “recorded” twice to their first sentence to make it correct.

Likewise, 1,200 fewer crimes being recorded does not mean 1,200 fewer occurred. There may have been more, the same amount, even fewer or anything in between. So we cannot say “that means X” about the actual impact of crime. We certainly can’t say “that means every day three less (sic) people were affected by crime”. 1,200 goes into 365 3.3, not 3, times. Many offences ‘affect’ more than one person. Many offences occur as part of one criminal act and so ‘affect’ the same person(s) at the same time.All of which means we can have no idea how many more or fewer people were affected by crime in the last year.

To top it off, even if the reduction were three a day on average that’s completely different to saying three fewer every day as the article does. On some days there could be more than three fewer  offences, on other days there could be less than three fewer or even more offences.

The crime rate in Auckland may be around 1000 recorded offences per 10,000 population but that does not mean one in every ten Aucklanders is likely to experience crime. Most crimes are experienced by a few people, who are victimised multiple times in a single criminal act and, often, repeatedly during a year. On the flip side, many crimes have more than one victim. So, again, just because the number of recorded crimes or rate of crime is known does not mean have any idea of the number of victims or rate of victimisation.

Even if the one in ten figure were correct, it wouldn’t mean “one in every 10” as the article states. Some randomly selected groups of ten would have more than one victim, others would have none. Same goes for “760 people in every 10,000”.

If journalists don’t understand statistics, they shouldn’t try to play fancy and pointless games with them. To the informed it merely reveals the journalists’ ignorance. For people who don’t know any better, the journalists just sows misinformation and misunderstanding.

the mathemagician

8 comments on “Statistical crimes and the media ”

  1. Ag 1

    I honestly don’t know why we bother with a free press.

  2. Rex Widerstrom 2

    That pottage of ignorance is a perfect indicator of the reason that, as an editor, I used to sort applications for reporting jobs into two piles – those who’d attended the majority of “journalism courses” and those who hadn’t. Then rejection letters would be sent to the former.

    There are notable exceptions, of course, but nowhere is the maxim “those who can do, those who can’t teach” better illustrated than in the preparation of young would-be journalists for a career writing just this sort of story.

    It used to be that subs and editors would leap on this stuff. Now stories are rarely subbed for anything but length, never accuracy, and editors seem to be employed to deal only with falling circulations and raising advertising costs (never realising, all the while, that the drivel passing under their noses and into their publications is a primary cause of the former).

    • BLiP 2.1

      A blast from the past (and off topic to boot) – are the the same RW what run a radio station in Wainuiomata briefly back in the early 80’s?

      • Rex Widerstrom 2.1.1

        Ye gods, I’ll never escape my past 😉 .

        Yes. Several in fact – Radio Alpha, Radio n, 2XK and Festival Radio. I believe I’m the only RW in the world, alas – and thus all triumphs and tragedies associated with the name can be sheeted home to me, damnit.

        captcha: Ramshackle Historie. Ain’t that the truth!

  3. BLiP 3

    Ahhhh – its all coming back to me now. Fond memories only, mate.

  4. John Dalley 4

    The trouble with statistics, is they are only as good as the information supplied.
    I always find it intriguing when it’s claimed we have the highest pregnancy or highest this or that in the world but you are assuming that the collection of data in other countries is as good or better that NZ.
    I would think that reprting of overseas date could be suspect at times!

  5. BLiP 5

    Whenever it comes to statistics one’s first consideration should be; “who is speaking and what is their agenda.”

  6. the sprout 6

    also on the topic of journalists’ rampant inumeracy there’s this great piece from Keith Ng

    http://publicaddress.net/system/topic,1724,onpoint_wrong_wronger_wrongerest.sm

Recent Comments

Recent Posts

  • New testing requirements for international maritime crew arriving in NZ
    The Government is moving to provide further protection against the chance of COVID-19 entering New Zealand through the maritime border.  “Yesterday I instructed officials to consult with the maritime sector around tightening of the requirements for international maritime crew entering the country,” Health Minister Chris Hipkins said.  “Ultimately, this will ...
    BeehiveBy beehive.govt.nz
    35 mins ago
  • Fast-tracked Northland water project will accelerate economic recovery
    The Government has welcomed the decision to approve a new water storage reservoir in Northland, the first of a number of infrastructure projects earmarked for a speedy consenting process that aims to accelerate New Zealand’s economic recovery from Covid-19.  The Matawii Water Storage Reservoir will provide drinking water for Kaikohe, ...
    BeehiveBy beehive.govt.nz
    2 days ago
  • Tokelau Language Week reminds us to stay united and strong
    Staying strong in the face of challenges and being true to our heritage and languages are key to preserving our cultural identity and wellbeing, is the focus of the 2020 Tokelau Language Week. Minister for Pacific Peoples, Aupito William Sio, says this year’s theme, ‘Apoapo tau foe, i nā tāfea ...
    BeehiveBy beehive.govt.nz
    1 week ago
  • NZ announces a third P-3 deployment in support of UN sanctions
    The Government has deployed a Royal New Zealand Air Force P-3K2 Orion (P-3) maritime patrol aircraft to support the implementation of United Nations Security Council (UNSC) resolutions imposing sanctions against North Korea, announced Minister of Foreign Affairs Winston Peters and Minister of Defence Ron Mark. “New Zealand has long supported ...
    BeehiveBy beehive.govt.nz
    2 weeks ago
  • Pacific trade and development agreement a reality
    Pacific regional trade and development agreement PACER Plus will enter into force in 60 days now that the required eight countries have ratified it. Trade and Export Growth Minister David Parker welcomed the announcement that the Cook Islands is the eighth nation to ratify this landmark agreement. “The agreement represents ...
    BeehiveBy beehive.govt.nz
    2 weeks ago
  • Securing a pipeline of teachers
    The Government is changing its approach to teacher recruitment as COVID-19 travel restrictions continue, by boosting a range of initiatives to get more Kiwis into teaching. “When we came into Government, we were faced with a teacher supply crisis,” Education Minister Chris Hipkins said. “Over the past three years, we ...
    BeehiveBy beehive.govt.nz
    2 weeks ago
  • Border exceptions for a small number of international students with visas
    The Government has established a new category that will allow 250 international PhD and postgraduate students to enter New Zealand and continue their studies, in the latest set of border exceptions. “The health, safety and wellbeing of people in New Zealand remains the Government’s top priority. Tight border restrictions remain ...
    BeehiveBy beehive.govt.nz
    3 weeks ago
  • First COVID-19 vaccine purchase agreement signed
    The Government has signed an agreement to purchase 1.5 million COVID-19 vaccines – enough for 750,000 people – from Pfizer and BioNTech, subject to the vaccine successfully completing all clinical trials and passing regulatory approvals in New Zealand, say Research, Science and Innovation Minister Megan Woods and Health Minister Chris Hipkins. ...
    BeehiveBy beehive.govt.nz
    3 weeks ago
  • International statement – End-to-end encryption and public safety
    We, the undersigned, support strong encryption, which plays a crucial role in protecting personal data, privacy, intellectual property, trade secrets and cyber security.  It also serves a vital purpose in repressive states to protect journalists, human rights defenders and other vulnerable people, as stated in the 2017 resolution of the ...
    BeehiveBy beehive.govt.nz
    3 weeks ago
  • Ministry of Defence Biodefence Assessment released
    The Ministry of Defence has today released a Defence Assessment examining Defence’s role across the spectrum of biological hazards and threats facing New Zealand. Biodefence: Preparing for a New Era of Biological Hazards and Threats looks at how the NZDF supports other agencies’ biodefence activities, and considers the context of ...
    BeehiveBy beehive.govt.nz
    3 weeks ago