The noise reduction widget shows the percentage of the all events correlated into Situations. You can view the noise reduction value in percentage and its trend on the Overview page as shown in the following example:

Event noise reduction computation
The following computation is used to derive the noise reduction value in percentage.
Noise reduction computation
noiseReduction(%) = ((secondaryEvents-primaryEvents)/totalEventsAssociatedwithServiceswithID)*100)
Consider the following example to understand how the noise reduction value is computed:
Total number of service associated events in the system (totalEventsAssociatedwithServices) = 50
Total number of ML-based situations in the system (primaryEvents) = 10
Total number of events associated with the ML-based situations in the system (secondaryEvents) = 20
noiseReduction(%) = ((secondaryEvents-primaryEvents)/totalEvents)*100) = ((20-10)/50)*100 = 20%
What are total events?
Total events are the events that are associated with a service and contain a Service ID.
What are primary events?
A primary event is an aggregated event derived from several matching events. For example, you can derive a single event from the secondary events listed in the following example: The host1.bmc.com host is shutting down. The primary event should match the following conditions:
- Class = Situation
- Algorithm Name = ML
- Relationships = evcount must be greater than 0 and the rstat value must be primary.

What are secondary events?
Secondary events are a set of matching events that can be combined to create a single aggregated event. For example, if the host1.bmc.com host is shut down, you may receive several events originating from that host as shown in the following example:
| |
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application1 is shutting down | The host1.bmc.com host is shutting down |
|
Unable to authenticate application3 |
Unable to open application5 |
The secondary event should match the following conditions:
Relationships = Must contain mlsituation and the relationships.rstat value must be secondary.
