問41
頻出度★★★
プロジェクトマネジメントにおいて計画を立てる際に用いられる手法の一つであり，プロジェクト全体を細かい作業に分割し，階層化した構成図で表すものはどれか。
平成24年度 春期 ITパスポート試験 問41
マネジメント系プロジェクトマネジメント › プロジェクトマネジメント
This question's explanation and your answers so far.
解説
問 41
Incorrectア
A DFD (Data Flow Diagram) is a structured-analysis notation that shows the flow of data within a business or system — where data is created, which processes it passes through, and where it is stored — using symbols for processes, data stores, data flows, and external entities. It is used in the analysis and design phases to grasp what the target business looks like; it is not a diagram for splitting project work into units of management. A DFD is also drawn hierarchically, refining a higher-level process into lower-level ones, but what is made hierarchical is processing and data flow, not project tasks, so it does not meet the conditions in the question.
- イ
正解 The correct answer is イ, WBS (Work Breakdown Structure). WBS stands for Work Breakdown Structure, known in Japanese as 作業分解構成図 (work breakdown chart); it is one of the most representative techniques and the starting point of project planning. You first place the whole project (the deliverable, or the project itself) at the top, break it down into major deliverables or phases, and then break those down further, step by step, creating a tree structure (a hierarchical structure diagram). The manageable units placed at the lowest level of the breakdown are called work packages; once the work is divided this finely, it becomes practical to assign people, estimate work time and effort, set schedules, and track progress. The principle when breaking work down is that at each level the higher-level task must be represented exactly by the set of tasks directly below it, with nothing missing and nothing extra (a higher-level task = the sum of the tasks directly under it), which prevents omitted and duplicated work. The list of tasks obtained this way also feeds directly into schedule creation (arrow diagrams and Gantt charts), cost estimation, assignment of responsibility (RAM / responsibility assignment matrix), and risk identification. Only WBS satisfies, as its very definition, all three conditions given in the question — used when making plans, breaks the entire project into small tasks, and represents them in a hierarchical structure diagram — so the answer is イ.
Incorrectウ
A state transition diagram uses shapes such as circles to represent the states a target (a system, a device, or an object) can be in, and arrows to show which state it moves to when a given event (an input or a condition) occurs. It is used to make clear the specifications of things whose behavior changes according to state, such as embedded systems, screen transitions, and communication procedures. What it expresses is how states change over time, not a hierarchical breakdown of work, so it is not a technique for identifying tasks during project planning.
Incorrectエ
A risk analysis sheet is a table that lists the risks anticipated in a project and organizes them item by item — probability of occurrence, degree of impact, priority, response measures (avoid, mitigate, transfer, accept), the person responsible, and so on. It is like WBS in that it is used in project management, but what it handles is risks rather than tasks, and its form is a table (a sheet) rather than a hierarchical structure diagram. It therefore does not fit the condition in the question of breaking the entire project into small tasks and representing them hierarchically.
ここがポイント
- The definition of WBS (Work Breakdown Structure) — a technique that breaks the entire project down step by step into small tasks and represents them in a hierarchical structure diagram (a tree structure). The units of management at the lowest level are called work packages, and they are the basis for assigning people, estimating effort, building schedules, and managing progress. Break the work down so that at each level the higher-level task is represented exactly by the set of tasks directly below it, preventing omitted and duplicated work.
- Tell confusable diagrams and forms apart by their purpose — a DFD is a structured-analysis diagram showing the flow of data, a state transition diagram shows behavior in terms of states and events, and a risk analysis sheet is a table for evaluating and organizing risks. Only WBS hierarchically breaks down the project work itself.
用語