The bus factor is how exposed you are if key people, perhaps with critical knowledge or skills, were hit by a bus.

Examples might include the only people able to keep a company running, restore a server from a backup, or someone who held the only key to unlock crypto assets of its customers. As a result, many places are set up with, or required to have by investors or insurers, some redundancy — say two experienced developers with knowledge of how a service works — to minimise the risk of a tragic accident also being a severe problem for a company or its customers.

As a metaphor, the bus factor may be helpful to consider without the need for people to actually be hit by a bus. It may be worth thinking through how you might operate if someone was late, missed their flight, was ill on the day, or simply quit. In operational roles, this will often lead to a minimum of two people for each key position if nothing else to allow one to take a break from time to time.

An alternative framing, with fewer fatalities, is 'what if we all won the lottery?' and so decided to go do something else.

Bus factor

In much of life we're used to things adding up — got one scoop of ice cream? Two is likely to be better. Buying one thing? Getting another free is probably a good thing. The dilution effect, however, illustrates an interesting action of our brain when evaluating our options. Niro Sivanathan showed that when displaying possible side-effects of drugs, if you were to add another side-effect, a minor one like 'itchy feet', instead of the extra negative side-effect increasing our overall perception of the risk of the drug it actually lowered it. So, people would deem a drug with the side effects heart attack, stroke, and itchy feet, as less risky than one with just heart attack and stroke.

In another clever experiment by Christopher Hsee at the University of Chicago, people were willing to pay less for a new dinnerware set when the set was actually larger but also included some broken items. Even though a set had more intact items the presence of a few broken ones decreased the set's perceived value.

And the same may be true when making an argument to persuade someone to see our point of view. If you have 2 strong points and 1 weaker one, your argument may actually be made weaker by adding the extra point. As Niro Sivanathan, an Associate Professor of Organisational Behaviour at London Business School, explains: Arguments don't add up. They average out.

Next time you're making your case, consider sticking to your strong arguments.

Hear Niro Sivanathan explain the dilution effect in his 10 min TED talk The counterintuitive way to be more persuasive

The paper: Sivanathan, N., Kakkar, H. The unintended consequences of argument dilution in direct-to-consumer drug advertisements.Nat Hum Behav 1,797–802 (2017).

The dilution effect

In Don Norman’s classic The Design of Everyday Things, Don gives an example of how to break into an office: just turn up at the door with a bunch of unwieldy computer equipment that looks difficult to carry and ask someone if they can open the door for you. Generally, someone will. Which goes to show no matter how well your system is designed, how seemingly impregnable your defences are, or how robust your processes, human risk — people doing things they shouldn’t, or not doing things they should — are most likely the biggest ones. Like accidentally leaning on the keyboard before sending a bank transfer.

The sketch is loosely based on a story, which is not true but illustrates the point nicely, that the Mongols got past the Great Wall simply by bribing the guards.

If you like behavioural science, cognitive biases and the like, and want to build a better understanding of human risk you might like the human risk newsletter run by a long-time patron of Sketchplanations Christian Hunt.

Human risk

People in the last year of a decade, say, 29, 39, 49, 59, are known as 9-enders — a term from Adam Alter and Hal Hershfield. While it could have been that one year is kind of like the next year, Adam and Hal propose that as we approach the end of a decade we are more likely to do a kind of meaning audit of our lives. And in the years just before the end of a decade, if we may have fallen short, or feel there’s something else we want to accomplish, we’re much more likely to do it then than in any other year of a decade.

In practice, as Dan Pink shared in his book When: The Scientific Secrets of Perfect Timing, these are, therefore, the times when we’re more likely to do something extreme like running a marathon for the first time and, sadly, also committing suicide.

Read more in Dan Pink’s Atlantic article: You’re Most Likely to Do Something Extreme Right Before You Turn 30, Dan Pink, The Atlantic

When: The Scientific Secrets of Perfect Timing, Dan Pink

People search for meaning when they approach a new decade in chronological age, PNAS, vol. 111 no. 48, Alter and Hershfield, 2014.

9-Enders

A microlife is thirty minutes of your life expectancy. You can use it up by chilling for 30 minutes or you could start to speed through them by smoking a few cigarettes or having a few drinks.

A simple way to bring difficult-to-grasp long-term, slow-burn risks into a unit that can motivate you and a handy way to compare risks.

Even better, you gain a microlife with 2-3 cups of coffee. Win!

Interesting? See Microlives: A lesson in risk taking, by Cambridge University Professor of risk David Spiegelhalter. Or see his 15 min TED talk: Motorbikes, Terrorism, Heart Attacks, Sausages: Professor David Spiegelhalter at TEDxOxbridge, or the full paper.

Microlife: The unit of life

A micromort is a one in one million chance of sudden death during the activity. You get a day of regular living for one micromort (though clearly that probably depends on what your average day is). Turns out you get a lot further per micromort by car, and that motorways are by far the safest form of road. You’ll experience 7 micromorts from running a marathon and 39,427 from climbing Everest.

Introduced by Stanford Professor, Ronald Howard.

Micromort: The unit of death

Your preference for risk - a psychological measure that changes slowly throughout our lifetime except for sudden shifts with big life events (eg losing a family member, having a baby).

Your capacity for loss - a situational factor that depends on your circumstances and, say, the context of the money you are taking a risk with. For example, if money is an unexpected bonus or gift, then you probably have a greater capacity for its loss, than if you earned it.

Both aspects are important. For example, some people are naturally daredevils on the ski-slopes, but even they may slow down a little when they have a family depending on them.

Sketchplanations tagged with risk