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In defense of 100%

∙ 5 min

One of my son's drawings

The Pareto principle is defined at Wikipedia as:

The Pareto principle states that for many outcomes, roughly 80% of consequences come from 20% of causes (the “vital few”). Other names for this principle are the 80/20 rule, the law of the vital few, or the principle of factor sparsity.

The business world people has taken liberties with this definition. The Pareto principle often becomes synonymous with an acceptence, before even attempting to solve a problem, that you will not find a perfect solution. That you should now, at the onset of our journey to build something that works, temper your expectations and get ready for a sub-optimal solution to the task at hand.

I started my relationship with this principle late in my career. The first part of my adult working life was spend in technology and engineering. 80/20 isn’t good enough when designing systems humans will use and building technical resiliency for critical applications. Yes, costs and timelines always play a role, but at a functional level, 80% isn’t good enough. 80% doesn’t build the cars people depend in the everyday grind as well as in emergencies. 80% doesn’t get rovers to Mars.

A younger version of myself had to grapple with the fact that idealistic ambitions of a perfect outcome can stop you from delivering anything. It makes the outcome binary: perfect or nothing. Or, at least, delaying until one achieves as close to perfection as is acceptable. This isn’t how the real world works.

Mediocraty, compounded

Something that has always has and continues to bother me about this “form of the 80/20” rule is its compounding effects. As an ex-engineer, let me use mathematics to illustrate my point. Let’s assume you always apply the 80/20 rule to problems you’re faced with (in other words, you frame the environment for problem-solving such that the 80% solution will suffice). I’ll assume that one solution has an effect on the next (and so multiply their efficacy together) and represent this as a limit.

$$ \lim \limits_{x \to \infty} 0.8^x = 0 $$

In plain English, 80% multiplied by itself infinite times decays down to 0. 80% of 80% is 64%, 80% of that is 51%, an so on. If you compound the 80/20 thinking x times, you eventually reach 0. Of course, any percentage you plug in to this equation will tend to 0: 80%, 90%, 95%. But this decay to 0 happens much more quickly with lower percentage bases. Use the table below to compare 10 interations, one with 80% and the other with 95%.

Iteration Compounding 80% Compounding 95%
1 80% of 100% is 80% 95% of 100% is 95%
2 80% of 80% is 64% 95% of 95% is 90%
3 80% of 64% is 51% 95% of 90% is 86%
4 80% of 51% is 41% 95% of 86% is 81%
5 80% of 41% is 33% 95% of 81% is 77%
6 80% of 33% is 26% 95% of 77% is 74%
7 80% of 26% is 21% 95% of 74% is 70%
8 80% of 21% is 17% 95% of 70% is 66%
9 80% of 17% is 13% 95% of 66% is 63%
10 80% of 13% is 11% 95% of 63% is 60%
0% 0%

I’m not implying that you can model real life with this simple table. Nor that decision-making and its consequences (positive and negative) can be represented by multiplying two numbers together. What I’m trying to convey is: going the extra mile and striving to do things right has positive consequences farther into the future than you may be considering. It helps preserve the quality, or slow the decay, of the outcome of all other related solutions: past, present and future.

And, conversely, constantly applying “good enough” thinking eventually results in a situation in which the compounded mediocraty of your solutions catches up to you. You may, as I have, find yourself in a situation you barely recognize. A set of solutions cobbled together with half-baked thinking, compounded. This all now forms the landscape of your working life. And your team’s working life, of course. This will often create ticking time-bombs for the future, or at best, areas you know you’ll have to rethink at some point because they’re going to crumble.

The right tool for the job

If used in the right situations, this variant of the 80/20 rule can be enormously valuable. For those who tend to be more detail oriented and have perfectionist tendencies (I consider myself a member of this group…at times), it can act as a useful mental anchor to keep the actual objective and boundary conditions in mind. It can help you make the big decisions faster without agonizing about the details. At least not too soon.

But beware not to adopt this mindset in a dogmatic way. It’s not the right tool for every job. And as much as it illicits head-nodding in meetings (because it sounds like a completely reasonable approach to problems), make sure you use it at the right time.

If all you have is a hammer, everything looks like a nail

And, conversely, switch into a mode of thinking that considers many more eventualities and details when that’s warranted.

And in the end, I beleive that’s where the real added value is: developing your mind to be able to operate in both modes and developing the decision-making to know when to apply which type of thinking.

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