問3
頻出度★★★
業務分析を行うときに, DFD を用いて検討するのに適しているものはどれか。
平成23年度 秋期 ITパスポート試験 問3
ストラテジ系システム戦略 › 業務プロセス
This question's explanation and your answers so far.
解説
問 3
Incorrectア
“The critical path of the business operations” is wrong. The critical path is the longest route that determines the overall duration when the tasks of a project are connected by predecessor-successor relationships (the route with zero float, on which a delay anywhere delays the whole project). To find it, you draw an arrow diagram (PERT chart) and calculate the earliest node time and the latest node time of each node. The arrows in a DFD merely represent the passing of data; they are not symbols for the duration of a task or for predecessor-successor ordering, so the length of a route cannot be calculated from a DFD.
Incorrectイ
“The work cost of the business operations” is wrong. To examine the cost of each task, you use estimation techniques that break the work down finely with a WBS and build up man-hours and unit prices, or techniques such as ABC (activity-based costing), which allocates indirect costs to each activity. The symbols of a DFD provide no mechanism for writing in quantitative attributes such as amounts of money, man-hours, or headcount; they can express only the structure of the flow of data, so a DFD is not suited to cost analysis.
Incorrectウ
“The work schedule of the business operations” is wrong. To examine and manage a schedule — from when to when, and in what order each task is carried out — you use a Gantt chart, which shows task periods and progress with horizontal bars, or an arrow diagram, which allows schedule calculation. A DFD has no time axis, and the arrows drawn in it indicate the giving and receiving of data rather than the execution order of the processes, so it cannot represent a schedule.
- エ
正解 The correct answer is エ, “the improvement points of the business flow.” A DFD (Data Flow Diagram) is a representative structured-analysis technique that captures and diagrams business operations or a system from the viewpoint of the flow of data. It uses only four kinds of symbols: the data flow (an arrow = the data that is passed around), the process (a circle = the processing that transforms data), the data store (parallel lines = the place where data is kept, such as a ledger or a file), and the external entity (a rectangle = the origin or the destination of data, such as a customer, a business partner, or another department). By combining them, a single diagram shows what data arises where, which processing it passes through, where it is stored, and who finally receives it. In business analysis you first draw the current operations (As-Is) as a DFD. Waste, duplication, and stagnation then surface in visible form: the same slip is transcribed over and over by each department, data travels back and forth only for approval, a data store that nobody refers to is still left in place. If you then draw the DFD of the desired state (To-Be) and compare the two, you can discuss concretely which processes should be merged or abolished and which flows should be shortened. In other words, what a DFD is good at is revealing the structure of the business flow itself and finding improvement points in it, so エ is the suitable one.
ここがポイント
- A DFD (data flow diagram) is a structured-analysis diagramming method that represents the flow of data within business operations using four symbols: the data flow (arrow), the process (circle), the data store (parallel lines), and the external entity (rectangle). By drawing the current state (As-Is) and the improvement plan (To-Be) and comparing them, it is used to pick out improvement points in the business flow such as duplication, waste, and stagnation.
- Use each diagramming method according to its purpose — a DFD for the flow of data, an E-R diagram for the structure of data and its relationships, an arrow diagram (PERT chart) for schedule calculation and the critical path, a Gantt chart for task periods and progress, and a flowchart for the branches and loops of a processing procedure. The key to this question is not to make a DFD, which holds no information about time or cost, examine schedules or costs.
用語