Several problem solving techniques are described in the ITIL v3 Problem Management process volume.
One of these techniques is the Pareto Analysis. Pareto Analysis is also commonly referred to as the 80/20 rule
Pareto Analysis (80/20) is a simple, statistical method to allow us to focus on specific problems that are causing the majority of issues
Pareto Analysis begins by defining the causes of problems in a given time period and that causes percentage of the total.
A cumulative addition is then performed. The 80% mark of the cumulative addition help us identify the major causes that are generating 80% of problems. These are the causes that should be investigated as a matter of priority.
Rather than a problem solving technique, Pareto Analysis helps us to understand where the effort should be concentrated/prioritized with regard to finding resolutions.