This blog is mainly about the governance and future of policing and crime services. (Police & Crime Commissioners feature quite a lot.) But there are also posts about the wider justice system. And because I am town councillor and political activist, local & national issues are covered a little, as well.

Tuesday, July 16, 2013

The politics of stats, trends & probability

I am no statistical expert and it is many years since I studied the application of Student’s T test, two tails and correlation coefficients to psychological experiments. But I have retained just about enough of what I learnt then and since (about targets, trend analysis and statistical process control) to be pretty darn fed up with how most politicians and members of the media treat data.

The ridiculous way in which the media and certain sections of the government are treating the results of Dr Bruce Keogh’s investigation into hospital care is an object lesson in how complex data sets are twisted into political rhetoric. Some of this is clearly about politics and for that I can almost forgive them. But when it comes to the proportion of this twisting that is down to plain ordinary ignorance, I really can’t!

And if you want to know what I mean about the Keogh report, read this blog post and please read it carefully. And in addition this article has just been published:
Report into 14 NHS hospitals rejects claims that poor care killed thousands
NHS medical director says it is meaningless to use mortality indicators to quantify actual numbers of avoidable deaths.
Keogh's report will say: "However tempting it may be, it is clinically meaningless and academically reckless to use such statistical measures to quantify actual numbers of avoidable deaths."
We entrust politicians with a huge amount of power which they wield on our behalf. They spend vast amounts of money, our money, on projects which the evidence shows (if they looked closely) were never going to work. It is time this ended. All politicians ought to have a good introduction to stats, trends and probability (and scientific methods, while they are about it) so that they are better able to make decisions that will actually make a real difference.

Now I am not saying that all politicians and members of the media are ignorant of such matters, but many are. The information on Payment by Results that I have uncovered in the last few days disturbs me. In fact it horrifies me that we may well be paying service providers for results that could simply be chance results rather than the robust outcomes of a better service.

I do not intend to make this blog post a long lesson in stats. Other people can do that far better than me. But here is just one idea: if you were to throw a dice a couple of dozen times, you would expect the numbers to come up in reasonably even quantities. Perhaps the four might have come up 5 times and the three just once. But you would not presume the dice was loaded. However, if you threw the dice a hundred times and the three only came up (say) 5 times and the four came up (say) 26 times you would begin to think something odd was happening.

Stats is simply about measuring when the threshold between chance and a real variation (a loaded dice in this example) is crossed. Without statistics, you cannot know whether an occurrence of (say) less teenage pregnancy (etc. etc.) is just a random chance or that something ‘significant’ has happened (i.e. it is NOT chance, or at least very unlikely to be).

I would hope that most people reading this, get this. But do most politicians? And journalists? What do you think?

And I won’t even start to talk about about systems theory, the role of blame and the fact that complex things really are complex!! (I will leave that for another blog post.)

But please… please can we have less of the ignorance around trends, evidence and chance occurrences and a bit more understanding that ‘wicked’ social (and medical) problems require some pretty darn ‘wicked’ solutions…

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