Outlier Detection Using IQR

=IF(OR(B2Q3+1.5*(Q3-Q1)),"Outlier","Normal")

Implementation Guide

This task equips data analysts with a statistically sound method for identifying outliers using the Interquartile Range (IQR). It is widely applied in quality control, financial analysis, and exploratory data analysis. By embedding the logic directly into Excel, analysts can flag anomalies without specialized statistical software. The approach improves data reliability before modeling or reporting. It is transparent, reproducible, and easy to validate during peer reviews. Analysts can pair it with conditional formatting to visually surface anomalies. The method works across datasets and scales well as new data points are added.

💡 Expert Q&A Insights

Q: How do I calculate Q1 and Q3?

Use QUARTILE.INC or PERCENTILE.INC. |

Q: Is this suitable for small datasets?

It works best with moderate to large samples.

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