問48
頻出度★★★
システム開発プロジェクトの品質マネジメントにおいて, 品質上の問題と原因との関連付けを行って根本原因を追究する方法の説明として, 適切なものはどれか。
令和4年度 ITパスポート試験 問48
ストラテジ系企業活動 › 業務分析・データ利活用
This question's explanation and your answers so far.
解説
問 48
Incorrectア
Setting control limits (upper and lower) and inferring the cause from events that deviate from them describes a control chart. A control chart monitors over time whether a process is stable (whether abnormal variation is present); it is not a method that associates problems with causes to systematically pursue the root cause.
Incorrectイ
Deleting the items that do not apply from a candidate list and narrowing down from the rest is an elimination-style idea; unlike a cause-and-effect diagram, it does not structurally associate and visualize the cause-and-effect relationship between the problem and its causes in a fishbone shape. It does not correspond to the name of any standard quality-management technique tested in the IT Passport exam, so it does not fit the intent of the question.
- ウ
正解 The correct answer is ウ. Organizing the candidate causes in the shape of a fishbone and examining the root cause describes a cause-and-effect diagram (also called a fishbone chart or Ishikawa diagram). In this diagram, the result you want to solve (the characteristic = the quality problem) is placed at the far right, and its causes branch out like the bones of a fish into large, medium, and small bones, so they are organized systematically. This lets you grasp at a glance the cause-and-effect relationship between the single problem and its many causes, so you can examine and pursue, without omission, which factor is the true root cause. It best matches the method the question asks for: associating a quality problem with its causes to pursue the root cause.
Incorrectエ
Classifying causes and deciding the priority of handling in order of the number of occurrences is the idea behind a Pareto chart (a focus-on-the-vital-few approach, ABC analysis). It prioritizes factors starting from those that occur most frequently; its purpose is to rank the order of handling, not to pursue the root cause from cause-and-effect relationships, which is where it differs from what the question asks.
ここがポイント
- A cause-and-effect diagram (fishbone chart / Ishikawa diagram) is a technique that, for a given result (characteristic), branches out its factors in the shape of fish bones, visualizes the cause-and-effect relationship between the problem and its causes, and thereby pursues the root cause.
- Distinguishing the QC seven tools: a control chart = monitoring whether a process is stable (control limits); a Pareto chart = focusing on the vital few in order of frequency; a cause-and-effect diagram = systematically drawing out the causes. Their purposes differ.
用語