Want to Run a Modified Z-Score in Excel?
QI Macros can do it for you!
Run a Modified Z-Score Outlier Test using QI Macros
- Click on QI Macros menu > Stat Templates >
Dixons Q - Grubbs Outlier Tests. - Click on the "Modified Z Score" tab.
- Input your data in column A and QI Macros will do the rest!
What is a Modified Z-Score Outlier Test?
A Modified Z-Score is used to identify outliers in a data set. It is a variation of the Traditional Z-score that is more robust to outliers, especially in smaller data sets or when the data is not normally distributed.
NOTE: (3) or more observations are required to successfully run this test.
The Modified Z-Score uses both the "Median" and "MAD (Median Average Deviation)" to automatically identify your outlier(s).
How do I conduct a Modified Z-Score Test in Excel using QI Macros?
- Input your data in cells A2:A31:
- Input your "Threshold" in cell E2 (Threshold value is typically 3.5, but can be modified as needed):
- Your "Median" and "MAD" will be calculated automatically in cells F2 and G2:
- Your "Abs. Difference from Median" in column B and "Modified Z-Score" in column C will also be calculated automatically:
- If cells in column B turn red, this indicates that the "Modified Z-Score" value is greater than the "Threshold" value in cell E2.
*This functionality will be included in the January 2026 version of QI Macros*
