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_docs/_user_guide/engagement_tools/campaigns/building_campaigns/targeting_users.md

@@ -65,7 +65,9 @@ For more information and best practices, refer to [Multivariate & A/B Testing][4
 
 Braze provides detailed audience statistics of the targeted channels in the footer. 
 
-For campaigns, select **Calculate Exact Statistics** to determine an accurate number for your reachable users as this will search through every user in your user base. For segments, the larger your user base is, the more likely the **Reachable Users** amount is a rough estimate. For more details, refer to [Calculating exact statistics]({{site.baseurl}}/user_guide/engagement_tools/segments/creating_a_segment#calculating-exact-statistics).
+For campaigns, select **Calculate Exact Statistics** to determine an accurate number for your reachable users as this will search through every user in your user base. The number of reachable users may decrease if you use a [Global Control Group]({{site.baseurl}}/user_guide/engagement_tools/testing/global_control_group/) or set up message eligibility.
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+For segments, the larger your user base is, the more likely the **Reachable Users** amount is a rough estimate. For more details, refer to [Calculating exact statistics]({{site.baseurl}}/user_guide/engagement_tools/segments/creating_a_segment#calculating-exact-statistics).
 
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