IPA IP 2023 Question 38
A question IPA Japan published in 令和5年度 ITパスポート試験 公開問題 問38, translated into English. ITPEC is based on the same exams.
Which of the following is an appropriate diagram that shows the relationship between the number of program steps and the number of defects of multiple similar projects in order to examine the quality targets of a system development project?
Explanation
Scatter diagram — it plots two quantities measured on the same items, here program size and defects per project, to show how they are related.
Each similar project becomes one point: its number of program steps on the horizontal axis and its number of defects on the vertical axis. If the points rise from left to right, there is a positive correlation (larger programs have more defects), and how tightly they gather around that trend shows how strong it is. From this the new project can set a quality target, such as the number of defects to expect for a program of its size.
Answer (b)
Why not others:
- •(a) Control chart — plots one measure over time between control limits to see whether a process is stable
- •(c) Cause and effect diagram — a fishbone diagram that arranges the causes behind one effect; it holds no measured values
- •(d) Pareto chart — bars sorted by size with a cumulative line, to find the few categories that matter most
Key rule: The relationship between two variables is a scatter diagram; a process over time against limits is a control chart; priorities among categories are a Pareto chart; causes of one problem are a cause and effect diagram.
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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.