How to Calculate Outlier
What is Outlier?
An outlier is a data point that lies far from other observations. The IQR method defines outliers as values below Q1 − 1.5×IQR or above Q3 + 1.5×IQR (mild outliers) or ±3×IQR (extreme outliers). The z-score method flags values more than 2–3 standard deviations from the mean.
Formula
- IQR
- Q3 + 1 — Q3 + 1
- Q3
- Q3 value — Variable used in the calculation
- Q1
- Q3 + 1 — Q3 + 1
Step-by-Step Guide
- 1Sort data and find Q1 (25th percentile) and Q3 (75th percentile)
- 2Calculate IQR = Q3 − Q1
- 3Lower fence = Q1 − 1.5 × IQR | Upper fence = Q3 + 1.5 × IQR
- 4Points outside fences are flagged as outliers
- 5Z-score method: z = (x − mean) / standard deviation; |z| > 3 is an outlier
Worked Examples
Frequently Asked Questions
What is Outlier Is A Data Point That Lies Far From Other Observations?
An outlier is a data point that lies far from other observations. The IQR method defines outliers as values below Q1 − 1
How accurate is the Outlier Is A Data Point That Lies Far From Other Observations calculator?
The calculator uses the standard published formula for outlier is a data point that lies far from other observations. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.
What units does the Outlier Is A Data Point That Lies Far From Other Observations calculator use?
This calculator works with inches. You can enter values in the units shown — the calculator handles all conversions internally.
What formula does the Outlier Is A Data Point That Lies Far From Other Observations calculator use?
The core formula is: Calculate IQR = Q3 − Q1. Each step in the calculation is shown so you can verify the result manually.
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