October 18, 2016

The lack of change is the real story

The Chief Coroner has released provisional suicide statistics for the year to June 2016.  As I wrote last year, the rate of suicide in New Zealand is basically not changing.  The Herald’s story, by Martin Johnston, quotes the Chief Coroner on this point

“Judge Marshall interpreted the suicide death rate as having remained consistent and said it showed New Zealand still had a long way to go in turning around the unacceptably high toll of suicide.”

The headline and graphs don’t make this clear

Here’s the graph from the Herald

suicide-herald

If you want a bar graph, it should go down to zero, and it would then show how little is changing

suicide-2

I’d prefer a line graph showing expected variation if there wasn’t any underlying change: the shading is one and two standard deviations around the average of the nine years’ rates

suicide-3

As Judge Marshall says, the suicide death rate has remained consistent. That’s our problem.  Focusing on the year to year variation misses the key point.

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Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »

Comments

  • avatar
    steve curtis

    Wasnt one of the issues that the Coroners were applying a very high bar for what they called suicide. Taking your own life isnt enough.

    9 months ago