Nudges, webforms and cookies

They can designed to be in your best interests (as in the libertarian paternalism espoused in Thaler’s and Sunstein’s book, Nudge) but also in someone else’s best interest.

One small way is the resetting of options of webforms. The next time you’re booking something, uncheck/check the boxes so as not to receive marketing mail, then make a mistake in e.g., your payment details before pressing submit. Watch what happens when the site loads the page again with a message saying to review that section – I bet all your details are still there, except the marketing options have reverted to the defaults of opting in.

I forget the company now (Eurostar, Opodo, ?) that I was using a lot sometime ago, but there would always be a ‘mistake’ on the form – I think it was the CVV number – and the page would reload with that bit blank asking me to try again. I’d retype the number (the same number as before) but in the reload process the marketing options had reverted back and needed changing again.

Anyway, I noticed today on the Brussels Airlines website, that when the page reloads after making an incorrect entry they keep everything for you – except for the frequent flyer number you’ve entered, which will need retyping if you happen to notice. A nice way to marginally lower some of their future airmile liability.

One of my favourite sites is, which recently has started to charge readers when they view more than 7 articles a month (as far as I can tell, this is only when your IP address is outside of the UK). However, simply going via your browser’s internet options to see the list of cookies, and deleting the one from will reset your count back to zero, which made me wonder – is this theft?

Party A clearly wishes to charge Party B for their product, but Party B is preventing Party A from conducting the process that will lead to an invoice being issued and this is done in a way that Party A can’t detect.

Party A’s process involves planting a tracking device on Party B however. But then Party B probably also implicitly accepts such an activity (I haven’t read through the T&Cs on the site, but presume it’s standard to have a line about ‘we may use cookies when you use this service’). Ultimately though, when Party B is not on the site, what is wrong with choosing to remove data files from her computer so as to no longer be tracked, even if that does stop the payment process from being triggered on a later return?

Healthcare expenditure -v- life expectancy

A smart way to reduce the risk of confusing correlation with causation, especially when comparing different countries, is to plot the two variables of interest over time.

Here’s a nice example, showing that it’s likely the US has a less efficient healthcare system than other rich countries, and that the low life expectancy is not due to other confounding variables (e.g., having a higher homicide rate – something which has actually decreased over the time period shown).

More here by Lane Kenworthy

The Guardian -v- Addison Lee

I was wondering why the London-based taxi firm, Addison Lee, had so many bad reviews all of a sudden on its iPhone app and so did a little googling. This Guardian article explains part of the controversy*, which concerns a quote by the company’s chairman:

“There has, as we all know, been a tremendous upsurge in cycling … These cyclists are throwing themselves onto some of the most congested spaces in the world … the influx of beginner cyclists is going to lead to an overall increase in accidents involving cyclists.

“The rest of us occupying this road space have had to undergo extensive training.

“It is time for us to say to cyclists, ‘You want to join our gang, get trained….”

The Guardian felt differently however, using as evidence the fact that motorists are responsible for up to 75% of collisions involving cyclists. Their source was an earlier Guardian article which contained this:

The data, which was analysed by the Transport Research Laboratory (TRL) …found that police attributed responsibility for collisions to … the driver solely in about 60%-75% of all cases, [with] riders solely at fault 17%-25% of the time … CTC said the report showed that the government needed to focus more on driver behaviour …”We believe this report strongly supports our view that the biggest problem for cyclists is bad driving.”

I don’t agree that the data supports that the view that the government should concentrate on driers [though this may be true]. The statistics reported relate to the probability that party x caused an accident given that an accident occurred. It can often be useful to analyse something with extreme numbers, so let’s do that.

Imagine there are 1,000,000 motorists, just 4 cyclists, and 3 collisions. Two of the collisions are the fault of the driver, and one is down to the cyclist. So 66% of accidents are caused by motorists, but this ignores the fact that there are relatively more drivers than cyclists (ok, a lot more given the numbers we picked). The bigger picture is that in this version of London a mere 1 in 500,000 motorists cause accidents, as opposed to a massive 1 in 4 cyclists.**

A related stat I remember: you have the same chance of dying on a 200-mile motorbike ride in the UK as you do of getting killed whilst serving for a single day in the British army in Afghanistan (a year or so ago).


* The actual source of bad reviews seems more likely to be by black cab drivers not taking kindly to their unique privilege of being able to use bus lanes being challenged – a challenge which I think has some merit.

**When I first heard about Monty and his 3 doors I didn’t guess to change door, so happy to receive a challenge on this way of looking at the stats…