A Pareto Chart is a bar chart that ranks categories from largest to smallest with a cumulative percentage line overlaid. It makes the 80/20 principle visible: in most situations, a small number of causes are responsible for the majority of the effect, and the Pareto chart shows exactly which ones.
Collect data on a problem, defect types, downtime reasons, complaint categories. Count the frequency of each cause. Sort in descending order. Plot as bars from tallest to shortest. Add a cumulative percentage line that shows the running total. The result reveals the vital few causes worth attacking first.
Without prioritization, improvement teams spread effort evenly across every problem and improve nothing meaningfully. A Pareto chart makes the priority obvious: the top two or three bars usually account for the majority of the pain. Fixing them delivers most of the benefit for a fraction of the effort.
Pareto charts belong at the start of every improvement cycle. Use them to focus problem-solving on the causes that actually matter, then use them again after countermeasures are in place to verify that the top causes have shrunk. Repeat, because the next Pareto will reveal the next set of vital few to attack.
The Pareto chart is one of the simplest and most effective tools in the lean toolkit. It replaces "we should improve everything" with "we should improve these two things first", and that focus is what turns improvement effort into measurable results.
