The Proximity and Lateness Rebound Effect

I have a habit of labelling any unintended consequence that works in the opposite way to the intended consequence as a rebound effect. With this in mind, I hereby declare the discovery of the Proximity and Lateness Rebound Effect.

The discovery is not mine of course, but the name is. I learnt of this bizarre social phenomenon here.

The Proximity and Lateness Rebound Effect (I would appreciate any better name suggestions) describes the offsetting behaviour of people to commuting distances. One would initially think that moving closer to their workplace, their relatives, friends or other regular destinations would reduce lateness, but in fact the opposite effect can potentially occur – as your commute decreases your lateness increases (in frequency - you are late more often).

Here’s my proposed theory as to why this may occur.

First, 100% punctuality is surely suboptimal.  Because each trip has a degree of uncertainty, if we budgeted for perfect punctuality we would have to allow for a commuting time under the worst circumstances every time.  We would be far too early most of the time just to ensure that we weren't once a minute late.

Now suppose that being a little late is not a big problem, but being quite late is a serious problem. We might say that we want to be less than 10 minutes late 70% of the time, and less than 20 minutes late 95% of the time.

If your commute is typically 50mins, but traffic congestion and delays mean that the trip takes less than 70mins 95% of the time, less than 60mins 70% of the time, and less than 50mins 50% of the time, you can budget for a 50 minute commute and meet your lateness expectations. You will be on time 50% of the time, more than 10mins late 30% of the time and more than 20mins late a mere 5%.

If instead your commute is a mere 10mins on average, with only a very small variation in time (say less than 2 minutes), and you budget 10mins for your commute you will far exceed your lateness requirement. Therefore you may start allowing less and less commuting time to get to your destination, and soon become accustomed to regularly being a little late, but never very late.

Because of the difference in trip variation, the person with the long commute needs to be more cautious to avoid being exceptionally late. Doing so increases the frequency that they arrive early. On the other hand, those with short commuting distances have very little chance of being extremely late, and therefore need to pay little attention to factoring in their commuting time and may regularly be a little late.

My personal experience of moving closer to work is just this. I almost treat the 10 minute commute as negligible, and am typically a little late to everything. Previously, when the commute was about 30 minutes I would ensure that I had budgeted enough travel time, with a little room for delays.