プラン

四分位数の計算機

データの五数要約（最小値、Q1、中央値、Q3、最大値）と、四分位範囲、箱ひげ図用の外れ値を求めます。

4 つ以上の値（カンマかスペースで区切る）

結果

値を入力して「計算」を押すと結果が表示されます。

公式

IQR=Q3−Q1\text{IQR} = Q_3 - Q_1

The spread of the middle half of the data.

x<Q1−1.5 IQR  or  x>Q3+1.5 IQRx < Q_1 - 1.5\,\text{IQR} \ \text{ or } \ x > Q_3 + 1.5\,\text{IQR}

A value outside these fences is an outlier.

この計算ツールの使い方

  1. Enter at least 4 numbers separated by commas, spaces or new lines.
  2. Press Calculate to get the five-number summary, the IQR and any outliers.

解き方付き例題

Eight test scores

Sorted: 2, 4, 4, 5, 6, 7, 8, 30. The median is (5 + 6) ÷ 2 = 5.5.

Lower half 2, 4, 4, 5 gives Q1 = 4; upper half 6, 7, 8, 30 gives Q3 = 7.5.

IQR = 7.5 − 4 = 3.5. The fences are −1.25 and 12.75, so 30 is an outlier.

よくある質問

Why does my spreadsheet give different quartiles?

There are several quartile methods. Sumzo uses the median-of-halves method taught in most schools; spreadsheet functions such as QUARTILE often interpolate instead.

Is the median included in the halves?

No. With an odd number of values the middle one is left out of both halves.

詳しく学ぶ