Interesting General Knowledge - Pareto's principle

I don't remember when I first heard of Pareto's principle, but I've always been fond of it. It was originally used to state that 80 percent of Italian income went to only 20 percent of the population, but has since been used as a rule of thumb for a myriad of other cases.

I think it fits very well in the software domain. The exact numbers are not the important fact, but rather as a guiding principle of what takes more time than the other.

 

It is not hard to think of a few examples that could follow the principle:

• Creating demo-ware software will take 20% of the time, creating production grade software will take 80%.
• Creating 80% of a system will take 20% of the time.
• 20% of a systems functionality will be used 80% of the time.
• Resolving 80% of the defects will take 20% of the time.
• Once you have done the 80% normal cases, fitting in the last 20% exceptional cases will take 80% percent of the time. 
• 20% percent of a systems developers create 80% percent of the working functionality (Hopefully not :) )

I know these are crazy numbers. And I know this is certainly not true in a lot of cases. But still, you'll benefit if you keep Pareto's principle in mind.