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I told you so! 100,000 tests was a foolish target

May 6, 2020 - 4:37pm

When people say “I hate to say I told you so,” they never mean it. I absolutely love to say I told you so. So, without further ado: I told you so.

I said last week, when we were all on tenterhooks waiting to find out whether Matt Hancock had personally stuck swabs up the noses of 100,000 people (subs, check this please), that it was going to be a “hotbed for Goodhart’s law”.

Goodhart’s law: as soon as a measure becomes a target, it ceases to be a good measure. You want schools to give children a good education, in some complex but real way; you notice that the schools that give children good educations tend to have lots of children getting high grades; so you tell schools that they all need to have 50% of kids get five A* to C grades at GCSE. And then you notice that suddenly lots of schools are getting the grades without the actual quality of education going up, because they’re gaming the system.

Or, you tell people that you absolutely must reach 100,000 tests by the end of the month, because you hope that the number of tests performed will be a good proxy for the quality of the testing regime and its effectiveness in fighting Covid-19. But then you notice that actually more than 40,000 of the tests you say you’ve performed have in fact not been performed at all but have only been mailed out, that the numbers tested dropped immediately back down, and that only 7% of those mailed to care homes have so far been carried out.

A couple of people suggested to me that the 100,000 target pushed the huge increase in testing; even if corners were cut and goalposts shifted, the overall regime has been boosted enormously, and it wouldn’t have been possible without that super-ambitious and very public target. They may be right; it’s a reasonable case to make.

But it strikes me that the goalpost-shifting and stats-juking was entirely predictable given the very public and simplistic measure, and that some relatively simple steps could have been taken to make a more nuanced metric or set of metrics that drive the improvement nearly as well but that capture more closely the thing you really care about.

(You can listen to me blethering on about all this on Radio 4’s More or Less, if such a thing appeals.)


Tom Chivers is a science writer. His second book, How to Read Numbers, is out now.

TomChivers

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Dougie Undersub
Dougie Undersub
3 years ago

It was a hostage to fortune for Hancock to adopt that target, although it has certainly galvanised the testing effort. It’s not a surprise to find that a significant number of people who claimed to desperately need a test can’t now be bothered to go out and get one.
Unfortunately, our beloved media inevitably adopted the target as an easy-to-understand number with which to beat the Government, irrespective of its actual significance in combatting the disease. Their disappointment when the target was seemingly met was palpable.

Neil John
Neil John
3 years ago

In any numbers game it’s always going to give someone a stick to beat you with, and with our venomous hateful press even achieving it won’t help.

Adrian Smith
Adrian Smith
3 years ago

What is most sad about it is how gutted MSM was when the figure exceeded the target on 30 Apr and 1 May and how obsessed they are now with pointing out it is below target. What matters is whether we have the testing capacity and associated logistics to support the testing strategy for the next phase. It is fairly clear we have the capacity, there are clearly still many wrinkles to iron out with the logistics, but they will get ironed out.

The really key question though is whether test, track and trace will really contribute to getting our country back to work, whilst avoiding overloading the NHS. I have my doubts. Indeed I fear the greater visibility it might give of how the virus starts to spread a bit more (as it is bound to do) will lead to rescinding of relaxations, which in turn will slow our path towards herd immunity, which without a vaccine is the only way back from a dire economic situation.

Jonathan Bagley
Jonathan Bagley
3 years ago

I was astounded when he came out with this. Hasn’t he taken Politics 101? I can only guess it was a most unpolitician-like attempt to motivate people: more befitting of a football manager, but showed a lot of b****, for which many people gave him credit. It was very funny when he announced 122k. Starmer must have been sick in a bucket. He should have stuck at 98k. He might have been a plucky loser and got away with it. The Government doesn’t need to do this. It should play with a straight bat. Most people know that Starmer and the MSM are Monday morning quarter backs. If Boris turned lead into gold, they’d say it was too heavy and too shiny, but for some reason, a large section of the public has a great affection for him.