問51
頻出度★★★
システム開発プロジェクトにおいて, テスト中に発見された不具合の再発防止のために不具合分析を行うことにした。テスト結果及び不具合の内容を表に記入し, 不具合ごとに根本原因を突き止めた後に, 根本原因ごとに集計を行い発生頻度の多い順に並べ, 主要な根本原因の特定を行った。ここで利用した図表のうち, 根本原因を集計し, 発生頻度順に並べて棒グラフで示し, 累積値を折れ線グラフで重ねて示したものはどれか。
令和6年度 ITパスポート試験 問51
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 51
Incorrectア
A scatter plot is a graph in which pairs of two quantities (for example, temperature and sales) are plotted as points to see whether a correlation exists and what the trend is; it is neither a bar chart of counts by cause arranged in order of frequency nor a line of cumulative values. Its structure differs from the chart described in the question.
Incorrectイ
A check sheet is a table (recording form) with frames or categories laid out in advance so that data can be easily recorded and tallied by item. It is a tool for collecting and tallying data, not a graph, and it does not overlay a bar chart with a cumulative line.
Incorrectウ
A cause-and-effect diagram (fishbone diagram) organizes the factors that influence a particular result (characteristic) by branching them out like the bones of a fish, in order to map out the structure of the causes. It does not arrange causes in order of frequency or show cumulative values as a line, and it is not a chart for comparing how high or low the counts are.
- エ
正解 The correct answer is “エ Pareto chart.” A Pareto chart is a graph that aggregates the count for each item (here, the root cause of a defect), arranges them as bars from left to right in order from the most frequent, and additionally overlays a line chart of the cumulative count (or cumulative percentage). The description in the question — “aggregates the root causes, arranges them in order of frequency and shows them as a bar chart, and overlays the cumulative values as a line chart” — describes exactly how a Pareto chart is constructed. Because it lets you visually grasp the tendency for a small number of major causes to account for most of the whole (the Pareto principle, the so-called focus on the vital few), it is well suited to identifying the main root causes that should be prioritized for countermeasures in preventing recurrence.
ここがポイント
- Pareto chart = a chart that overlays a “bar chart arranged from the highest count to the lowest” with a “line of cumulative values (cumulative percentage).” It shows that a small number of major items account for most of the whole, and is used to identify the items that should be prioritized for countermeasures (focusing on the vital few).
- Distinguishing the seven QC tools by purpose: scatter plot = correlation between two quantities; check sheet = recording and tallying data; cause-and-effect diagram = organizing the structure of causes; Pareto chart = order by frequency plus cumulative values to grasp the priorities.
用語