問63
頻出度★★☆
データの尺度を名義尺度, 順序尺度, 間隔尺度, 比例尺度の四つに分類したとき, 間隔尺度に該当するものはどれか。
令和7年度 ITパスポート試験 問63
テクノロジ系基礎理論 › 応用数学
This question's explanation and your answers so far.
解説
問 63
Incorrectア
“School year (grade)” can be put in order (a magnitude relation) as 1st year → 2nd year → 3rd year, but the difference between grades does not represent a fixed quantity, so the interval itself cannot be said to be meaningful. It corresponds to an ordinal scale, which only allows ordering, not an interval scale.
Incorrectイ
“Blood type” (A, B, O, AB) is merely a label for classification, with no order or magnitude relation, and computing differences or ratios is meaningless. It corresponds to a nominal scale, which only allows classification, not an interval scale.
- ウ
正解 The correct answer is “ウ Time of day”. An interval scale is one in which, beyond the magnitude and order of values, the intervals (differences) between graduations are equal and meaningful, but the origin (zero) is set merely for convenience, so ratios are not meaningful. For time of day, the interval of one hour is equal everywhere, and the difference between 3 oclock and 5 oclock (2 hours) carries the same meaning as the difference between 10 oclock and 12 oclock. On the other hand, 0 oclock is not an absolute zero but only a conventional reference point, so a ratio calculation such as “6 oclock is twice 3 oclock” is meaningless. The property that differences are meaningful while ratios are not is exactly what fits the definition of an interval scale, so ウ is correct.
Incorrectエ
“Sleep duration” has an absolute origin of 0 hours (absolute zero), and a ratio such as 4 hours being twice 2 hours is meaningful. Because not only differences but also ratios are meaningful, it corresponds to a ratio scale rather than an interval scale.
ここがポイント
- Distinction among the four scales: nominal scale (classification only) < ordinal scale (ordering possible) < interval scale (differences are fixed and meaningful, but the origin is arbitrary) < ratio scale (has an absolute zero, so ratios are also meaningful). The higher the scale, the more operations are permitted.
- The decisive factor between an interval scale and a ratio scale is whether there is an absolute zero point and whether ratios are meaningful. Things like time of day and Celsius temperature, where differences are meaningful but ratios are not, are interval scales; things like length, weight, and duration, where ratios are meaningful, are ratio scales.
用語