Normalized Mutual Information (NMI)
Definition
NMI compares groupings based on their shared information content.
A normalized similarity measure based on mutual information, often used to compare cluster assignments.
Simply explained
The measure shows how similar two orderings of the same items are, even if the group names differ.
Why it matters in practice
Helps realistically assess model quality, limits, and technical decisions.
Example from business
A clustering solution is compared with known groups without directly assigning cluster labels.
Limits and pitfalls
- Mixing NMI variants or interpreting high agreement as semantic quality of clusters are mistakes to avoid.
Origin & history
NMI connects information theory with cluster evaluation; several normalization variants are common.
Use in mid-sized companies
- Possible example: A clustering solution is compared with known groups without directly assigning cluster labels.
Frequently asked questions
What does Normalized Mutual Information mean?
A normalized similarity measure based on mutual information, often used to compare cluster assignments.
Which mistakes should be avoided?
Mixing NMI variants or interpreting high agreement as semantic quality of clusters are mistakes to avoid.
Sources
Source checked on 10.10.2026. Editorial application examples are hypothetical; no evidence of real customer results.
Editorially reviewed on: