Interquartile Range and Outliers
Find IQR and the conventional 1.5-IQR outlier fences.
Your numbers
Interquartile range
Fences are descriptive screening rules, not proof that a value is erroneous.
Scenario comparison
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Formula
Use IQR = Q₃−Q₁ with fences Q₁−1.5IQR and Q₃+1.5IQR. Q₁ and Q₃ are lower and upper quartiles using linear interpolation. Values beyond the fences are flagged, not automatically treated as errors.
Find IQR and the conventional 1.5-IQR outlier fences.
Worked example
- Observations
- 1, 2, 3, 4, 5, 100
- Interquartile range
- 2.5
- Lower fence
- -1.5
- Upper fence
- 8.5
- Observations outside fences
- 1
Scope and limitations
Fences are descriptive screening rules, not proof that a value is erroneous.
Inputs are checked for missing values and allowed ranges. A result outside the finite numeric range is not displayed. Rounding affects display, while the calculation uses the model’s numeric precision.
Check your units and assumptions before relying on a result. Changing a label does not convert a currency or physical unit.
Formula version: 4037db0272bd · Example checked: