Apples, Oranges and other fruit

One of the most striking features of human cognition is how bad we are at doing the math(S) – despite the efforts of our high school teachers and those long winter nights learning algebra and calculus.

Most humans – even those you might think of as the more numerate, doctors for example – are pretty poor at doing the heavy lifting of calculation.

This was the striking finding of some of Kahneman and Twersky’s early collaborations: they discovered that doctors and other health care professionals were no better than their patients at working through outcomes from probabilities.

K&T put this down to what they called the Lazy Mind model (for a while at least): thinking is energy hungry so our minds have evolved to use short hands (yep, heuristics again). Feels like the right kind of answer is pretty good…

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Most of us don’t do very well at number rounds in quiz land – that’s the secret behind both Numberwang (spoof) and Countdown (real). Curiously, those who do well at the latter often use a “chunking” strategy to do the calculating which deliberately parallels the ‘natural’ approach but in a somewhat more considered and careful manner.

Back in real life, we tend to respond to numbers in this approximate way, rather than a precise way: big vs. small; bigger vs. smaller etc.

We also get hooked – or anchored – on these approximate perceptions so that what follows is understood in the context of the anchoring number (that’s why people always prefer data in terms of a time series that goes up or down – even grown-ups financial professionals).

Take the current scandal of HMG and PPE provision (it really is the gift that keeps on giving):

Under pressure to signal (note not ‘evidence’) that personal protection equipment supplies are both improving and now reaching the level that is needed, government spokespeople keep mentioning the number 1BN.

Hard to imagine what a billion anything looks like.

Seems like a really big number, doesn’t it?

Sounds like the kind of number that should do the job.

Except that it isn’t anywhere near enough

You and I can’t be expected to know what’s actually needed every day – what is the running rate of PPE needed in normal times for an average hospital?

“Other countries, such as France, have released weekly usage stats for some forms of PPE (they use 45 million masks a week, in case you were wondering). Scaling up (one small regional health) trust’s numbers would point to UK weekly usage of 55 million, a similar order of magnitude”

BBC News

So then you learn that half of this is gloves.

And the Department of Health has been double counting – each pair of gloves is counted as 2 items.

And that’s what the repeated reciting of ONE BILLION exploits.

Sounds a bit Dr Evil, no?

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Mike Myers

To some this doesn’t matter, but to those who already have a more critical stance towards the government’s management of the crisis (see yesterday’s post) it creates further distrust. And fuels further discussions about why the people supposedly there to protect us…

And then it’s revealed that the government have double counted: a pair of gloves is counted as two items.

It’s not apples and apples, is it?

It’s just a big old fruit mess.

And where does that leave the government’s ambition to signal progress in providing PPE?