問44
頻出度★★★
作業項目の順序関係や依存関係を表すことができ, プロジェクトのスケジュール作成において使用する図として, 適切なものはどれか。
平成25年度 春期 ITパスポート試験 問44
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 44
- ア
正解 The correct answer is ア, the arrow diagram. An arrow diagram (PERT chart) represents each activity with an arrow, and represents the breakpoints that serve as the start and end of activities with junction points (nodes); by joining the arrows at these nodes, it shows as a network the sequence and dependency relationships of “which activity cannot be started until which other activity is done”. If the required number of days is written on each arrow, the duration of each path from start to finish can be calculated, so you can obtain the critical path, which is the path that takes the most days (if activities on this path are delayed, the whole project is delayed), as well as the slack days of each activity. It can therefore be used directly for creating a project schedule and managing the work process, and it matches the condition in the question of a diagram that can represent sequence and dependency relationships and is used in creating a schedule. It is also worth remembering the following contrast: a Gantt chart, which shows the duration of each activity as a horizontal bar, is good for grasping progress but is poor at expressing dependency relationships, so when you want to handle dependencies, the arrow diagram is the one that gets chosen.
Incorrectイ
A control chart plots measured values such as product dimensions or defect rates in time order, and draws a center line together with upper and lower control limits in order to judge whether the variation is within the range of chance causes or is due to an abnormal cause; it is a diagram for quality control. It does have a time axis, but what it expresses is the variation in process quality, not the sequence or dependency of work items, so it cannot be used to create a schedule.
Incorrectウ
A cause-and-effect diagram (fishbone diagram) breaks the causes (factors) behind a given result (characteristic) down into major and minor bones, arranges them in the shape of a fish skeleton, and is used to identify the causes of a problem. Its arrows indicate the causal relationship between causes and a result, not the order in which activities are carried out or the predecessor-successor dependency between them, so it does not serve as a tool for creating a schedule.
Incorrectエ
A Pareto chart arranges counts such as the number of defects or the number of complaints by category as bars in descending order of size, and overlays a line showing the cumulative percentage; it is used to find the small number of items that should be tackled first (a priority-focused approach). The order in which the items are lined up is determined by the size of the counts, not by the chronological order of activities, and it cannot express dependency relationships either.
ここがポイント
- An arrow diagram (PERT chart) represents activities with arrows and breakpoints with junction points, showing the sequence and dependency relationships of activities as a network; from the required number of days it lets you obtain the critical path and the slack days, and it is used for creating a project schedule and managing the work process.
- The control chart, the cause-and-effect diagram, and the Pareto chart all belong to the seven QC tools and are diagrams for quality control; their purposes are, respectively, judging process abnormalities, identifying causes, and pinpointing priority items, and none of them expresses the sequence or dependencies of activities (distinguish them by their purpose).
用語