IPA IP 2024 Question 51
A question IPA Japan published in 令和6年度 ITパスポート試験 公開問題 問51, translated into English. ITPEC is based on the same exams.
In a system development project, it has been decided to perform a defect analysis in order to prevent the recurrence of defects found during testing. The test results and the details of the defects were entered in a table, and after the root cause of each defect was identified, the defects were aggregated by root cause and arranged in descending order of frequency of occurrence, and the main root causes were identified. Among the charts used here, which of the following is the chart in which the root causes are aggregated, arranged in order of frequency of occurrence and shown in a bar graph, and the cumulative values are superimposed on it in a line graph?
Explanation
Pareto chart — root causes as bars in descending order of frequency, with a line of the cumulative values over them.
The analysis in the question runs in three steps, and each uses its own chart:
- •Recording the test results and the details of each defect in a table is the job of a check sheet
- •Tracing each defect back to its root cause can be organised in a cause and effect diagram
- •Counting the defects per root cause, sorting the bars from the most frequent and adding a cumulative line is a Pareto chart
On the Pareto chart the cumulative line rises steeply over the first few bars: those few root causes account for most of the defects, so dealing with them first prevents the most recurrences.
Answer (d)
Why not others:
- •(a) Scatter diagram — plots pairs of two quantities as points to show whether they are correlated; it has no categories sorted by frequency and no cumulative line
- •(b) Check sheet — a form for recording occurrences as they happen; it collects the data the Pareto chart is drawn from but draws no bars or cumulative line
- •(c) Cause and effect diagram — the fishbone diagram arranges the possible causes of one effect in branches; it shows no counts, so it cannot rank the causes
Key rule: Sorted bars plus a cumulative line is a Pareto chart, used to pick the few causes to tackle first; a check sheet records, a fishbone diagram lists causes, a scatter diagram shows a correlation.
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This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.