Skip Navigation U.S. Department of Health and Human Services
Agency for Healthcare Research Quality
Archive print banner

Slide Presentation from the AHRQ 2007 Annual Conference

This information is for reference purposes only. It was current when produced and may now be outdated. Archive material is no longer maintained, and some links may not work. Persons with disabilities having difficulty accessing this information should contact us at: Let us know the nature of the problem, the Web address of what you want, and your contact information.

Please go to for current information.

Why Cluster?

Text Description is below the image.
  • Clusters show us event reports that are similar across predefined dimensions
  • They may represent:
    • frequency of a type of event
    • event trends in time
    • potential prevention, etc

Image shows the same set of dots clustered into different groups of smaller size from left to right.


Frequency of a type of event: Many of the same type of incidents can be a bad sign. A rare incident may also be noticed.
Event trends over time: You could plot similar events in a cluster over time to see if things are getting better or worse.
Potential prevention: You can see what has worked in previous, similar incidents in the past and try to apply it in new events.

One way to create statistically significant clusters is to start with all the data in one cluster, and then systematically (using an algorithm) add to or remove elements from the cluster, so that its statistics improve.

Previous Slide Previous Slide         Contents         Next Slide Next Slide


The information on this page is archived and provided for reference purposes only.


AHRQ Advancing Excellence in Health Care