What is the 80/20 rule and why does it work?


What is the 80/20 rule and why does it work?

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‘The 80/20 rule’ is less a rule and more an observed trend. It states that when you divide things in an approximate half, you can often observe an 80% distribution of a related statistic on one half, and 20% on the other.

One example is Chinese land area, where approximately 80% of their inhabitants live in the eastern half of the country, and 20% in the west.

The 80/20 rule states that 80% of the work will take 20% of the time, and the remaining 20% of the work, will take 80% of the time.

This is to illustrate both that, when you get close to finishing a project, it is the finer details that end up bogging you down. Also when you feel like you are half way through a project, you are usually nowhere near it.

The 80/20 rule helps project planners to figure out the true deadline.

The 80/20 rule is that 80% of the time and effort of a job or task goes into the last 20% of finishing it. Or looking at it from the other direction, it only takes 20% of the total effort to get you 80% of the way to the finish line.

It’s not a measurable, scientific truth, but it’s good shorthand for time / project management. It’s just a reminder that the devil is in the details — You might be able put a first draft together pretty quickly, something that gives you a sense of what the finished product is going to look like, but your work is still just getting started at that point.

I like to imagine it like sculpting a statue from a solid block. Early on you’re carving big chunks out at once, and you can start to see the shape of the figure. But at the end, you’re zoomed way in on one detail, putting in a ton of effort just to carve out individual eyebrow hairs or something. The same is basically true of any task — whether it’s cleaning a house, developing a video game, writing a book, or whatever.

Some people have explained what it is, here is a shot at why it works:

First, a project can be divided into many different tasks. Each task requires some amount of effort, and contributes some amount of completedness to the project.

At the beginning of the project, 0% of the total effort has been done, and 0% of the total completedness of the project is done. At the end, 100% of the total effort has been done and 100% of the total completedness has been done (in both cases, percentages are out of what actually was done, not out of what was planned). As the project goes from the first state to the second, there will reach a point when the two percentages add up to 100%

In general, the earlier tasks tend to be more impactful for the effort they take, while the later tasks tend to be less impactful*. This means that the point where effort+completedness=100% will usually be somewhere between 50:50 and 100:0. 80:20 is a nice round midpoint.

*When this is not the case, it usually results in the project failing

There’s other examples of 80/20 rules as well. Usually to do with the behavior of individuals at the extreme of a bell curve as a subset of a group.
80% of alcohol is consumed by the 20% of people that drink the most

80% of medical costs (US) is incurred by the 20,% of people that consume the most medical services.

I bet 80% of Wikipedia edits are made by the 20% most active users.

80% of political yard signs are posted by 20% most politically active people (I made this up, but would bet $1 it’s true).

80% of reddit comments made by 20% of users? Also would bet $1 this is true.

I’m sure there are other examples.