Let’s start with a quiz. If you have a machine with 200 parts, each of which operates independently and is 99% reliable, how reliable will the overall machine be?

95% ? 80%? 99%? Nope, nope, and nope. It’s somewhat shocking to learn that it’ll only be around 13% reliable, running just 13 hours out of every hundred it should. Truly terrible.

The math is relatively simple (you multiply the probability that each of the 200 variables will fail by one another), but the lesson here isn’t that you should take a journey to your long-forgotten stats class. It’s that keeping processes simple is nearly always the best policy. Mistakes compound across a process to make an organization overall much less effective than any one of its individual parts. So the fewer parts your processes have, the better.

If you run a factory or a science lab, you likely think about these sorts of problems each day. But for those of us who don’t, this little bit of mathematical insight can pay dividends.

Imagine, for example, that you run a bike rental company. Most of your employees are pretty good, but none are perfect. Most of your bikes are pretty good, but there may be a few in the fleet that don’t shift gears quite right. And most of the helmets you rent to your customers are just fine, but one or two have a broken buckle.

With those potential deficiencies, how likely is it that a customer will have a flawless experience? Let’s put some numbers into play. Say for example that employees will size a customer correctly for a bike 95% of the time. Assume also that out of the 50 bikes in your fleet, 45 of them (90%) are in perfect condition, while five have shifters that get stuck. And finally pretend that most of your 50 helmets are good to go, but only 46 of them (92%) have a buckle that works. The equation to determine the probability of your customer having a perfect experience looks like this:

In this scenario, a customer will only end up with a correctly sized bike that shifts well and a helmet that’s in good shape 79% of the time.

While it’s tempting as a business owner to add something extra into an experience or one more piece into a complicated business puzzle, we might do better to think about how much complexity that new idea will add to the process and how well we can reliably accomplish that task.