Outlier Detector

All statistics tools

Identify anomalous data points using Tukey's Fences method.

Data Entry

Enter Dataset (Comma or space separated)

Outlier Analysis

Outliers Detected

100

Extreme

Lower Fence6.88

Upper Fence17.88

1st Quartile (Q1)11.00

Interquartile Range (IQR)2.75

3rd Quartile (Q3)13.75

Sorted Data Preview

10,10,11,11,12,12,13,14,15,100

About this calculator

Overview

Tukey's Fences is a method for identifying outliers in a dataset using the interquartile range (IQR). It defines 'fences' beyond which data points are considered outliers. Points between 1.5x and 3x IQR are 'mild' outliers, while points beyond 3x IQR are 'extreme'.

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Pro Tips

Always investigate the source of an outlier before deciding to remove it.
The IQR method is robust to outliers because it's based on the median and quartiles, not the mean.
For small datasets (n < 5), outlier detection is generally unreliable.

Mathematical Formulas

Standard (Mild)

Q ± 1.5 * IQR

Extreme Outlier

Q ± 3.0 * IQR