Which diagram is used to identify the most frequent causes of problems so that improvement efforts can be targeted?

• A. Histogram
• B. Control Chart
• C. Pareto Diagram
• D. Scatter Diagram

Answer: (C)

The main idea here is prioritizing improvement efforts by focusing on the causes that occur most often. A Pareto diagram does exactly that: it places the causes of problems in order from most frequent to least and adds a cumulative line to show how much of the total is accounted for by the top causes. This makes it clear which few issues are driving the majority of problems, so you can target improvements where they’ll have the biggest impact, often aligning with the 80/20 rule. To use it, you collect data on each cause, count how often each occurs, sort from highest to lowest, draw bars left to right, and add a cumulative percentage line to see where the cumulative impact reaches a meaningful threshold. Other diagrams serve different purposes—histograms show overall distribution of a single variable, control charts monitor process performance over time, and scatter diagrams illustrate relationships between two variables—so they don’t directly highlight which causes to address first.