The Pareto Principle is a fancy name for the 80-20 rule.
I saw a tweet by @juixe (or rather a blog post mentioning the tweet) that said:
“Cut out the 20% from Pareto’s Principle from your process.”
So I did just that.
If 20% of the work takes 80% of the time, suppose you had a job that took 100 hours to accomplish.
80% of the work would be done in 20 hours.
The remaining 20% of the work will take the remaining 80 hours.
Now, it’s a given that you don’t know which 20% that is up front. So if you cut hours across the board (or randomly, assuming an optimal distribution), you’d decrease work in an evenly distrubuted pattern. That is 80% of your savings affects the easy part (or 16%) and 20% of your savings affects the hard part (or 4%).
The easy part (20 hours work) is thus reduced by 16% to 16.8 hours.
The hard part (80 hours work) is then reduced by 4% to 76.8 hours.
For a total savings of 6.4 hours work.
This shows why you shouldn’t try to cut scope.