Thursday, 29 July 2010


I have two things to say about queues today. The second one is inspired by Steven Landsburg, and I was reminded of it by the fact that I spent 40 minutes of today standing in a queue to get on the London Eye. Time which was essentially deadweight loss to the world.

The first is simpler, and I was inspired to write it by AJ Jacobs. AJ Jacobs is the author of The Year of Living Biblically, and I'm currently reading his new book "My Experimental Life". He's one of those journalists, who does crazy things and writes about them (he claims because he has nothing interesting in his past to write about - although why he can't just make stuff up like everyone else, I don't know). Anyway, the chapter of the book I was just reading is called The Rationality Project. Jacobs, having read Predictably Irrational and Nudge (but no doubt not having actually read Tversky and Kahneman) decides to rid himself of all of his irrational biases. He fails in funny ways, of course, and has a few interesting things to say along the way.

Anyway, at the end of the chapter he has a few points to make. Things he does differently since spending a month trying to be as rational as possible. Some of these are sensible: "I read menus from the bottom up" (because they are designed to be read from the top down - and are carefully designed to 'nudge' you into buying whatever the restaurant wants you to buy that day); "I spend a few minutes each week reading Michelle Malkin's conservative musings" (because he disagrees strongly with Michell Malkin, and only reading things by people you agree with is a sure way never to change your mind).

The one that I take issue with is this: "I make a note every time I'm in a fast moving grocery line". Now, the idea behind this is obvious:
We all are predisposed to notice and remember the bad stuff... when we're on a checkout line behind an eighty-two year old man paying with a sack of pennies and nickels.
But it's a really, really bad example to choose of this particular phenomenon because we actually do spend more time in slow-moving queues than in fast-moving queues. This is obvious once you think about it: slow-moving queues move slower! So if all queues were the same length, but with random speeds (which were impossible to predict before you join) you would still spend most of your time in slow-moving queues. You're just as likely to choose a fast queue, but every time you do choose a fast queue, you get to the front of it quicker.

If you want to avoid believing in the signficance of random events, you should make a note of every time you take your umbrella out and it does rain (or choose not to take it and it doesn't). You should remember every time you have a really strong feeling that you're about to get a phonecall from your grandmother and then you don't, or every time you meet someone who doesn't share your birthday.

I said I had two things to say about queues, but it's late, and I've spent longer than I expected writing about that one. I'll do the other one tomorrow.


T_Beermonster said...

The statement that we spend more time in slow moving queues is true on a per-queue basis but not necessarily on a per-task basis (or indeed on a global basis).
I need stamps and I need to obtain cash (maybe to buy stamps, maybe to buy beer).
I can stand in a slow queue at the Post Office and get both. Or I can stand in faster queues at the ATM and the stamp machine. Provided the slow queue is more than half as fast as the fast queues then I will spend less time queueing in the slow queue.
If I happen to have a parcel I want to post using the stamps then the slow queue is the best choice because I will have to stand in it for one task anyway.

One of the reasons queues may be slow is that the queues are multifunctional. Having me and many others standing at the counter performing multiple transactions ensures the queue remains slow, but may make it time-effective for those with multiple transactions.

John Faben said...

This is true, but I think it's beside the point. When people complain that they "always pick the slowest moving queue", I don't think they're saying that they accidentally choose to go to the Post Office rather than the ATM.

I think they're talking about those situations in which they have a choice of otherwise identical queues (eg, supermarket, bank, airport check-in). It is in these situations that you will find yourself spending a lot of time in slow-moving queues purely because they're slow-moving.

Of course, this could be solved by adopting a single-queue multiple server model (as they have, for example, at Primark), but that means *really* long-looking queues, which I think tends to put people off.