問50
頻出度★★★
時間を横軸にし，タスクを縦軸に取って所要期間に比例した長さで表した工程管理図はどれか。
平成21年度 春期 ITパスポート試験 問50
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This question's explanation and your answers so far.
解説
問 50
Incorrectア
An E-R diagram (entity-relationship diagram) is a data model diagram used in database design and similar work to show entities and the relationships between them. It expresses neither a time axis nor the required duration of an activity, so it is not a process management chart.
Incorrectイ
An arrow diagram (PERT chart) is a network diagram that represents activities as arrows and the boundaries between activities (nodes) as circles, showing the order of and dependencies between activities and the critical path. It is used in process management, but the arrow lengths are not proportional to the required durations and it does not take time on a horizontal axis, so it is not the chart described in the question.
- ウ
正解 A Gantt chart lists the activities (tasks) along the vertical axis and time (dates, weeks, and so on) along the horizontal axis, drawing each activity from its start to its finish as a horizontal bar whose length is proportional to the required duration. The chart that satisfies the three conditions in the question — time on the horizontal axis, tasks on the vertical axis, and a length proportional to the required duration — is the Gantt chart, so the answer is ウ. The length and position of each bar make every activity schedule visible at a glance, and by drawing actual results on top of the plan you can also see visually whether work is behind or ahead of schedule, which is why it is used as a representative tool for schedule and progress management in projects.
Incorrectエ
A state transition diagram shows the states that a system or object can take and, when an event occurs, which state it moves to. It only shows changes of state; it does not express time lengths such as when each activity starts or how long it takes.
ここがポイント
- Definition of a Gantt chart: vertical axis = activities (tasks), horizontal axis = time, bar length = required duration. It lets you grasp the schedule and progress of each activity at a glance and is used for progress management in a project.
- Identify a diagram by its purpose: process and schedule management uses a Gantt chart or an arrow diagram (PERT chart, which shows the order of activities, their dependencies, and the critical path); data structure uses an E-R diagram; the flow of processing or goods uses a flow diagram; and changes of state use a state transition diagram. A different diagram is used for each purpose.
用語