If you want to find and add to your recipient list a random subset of your topic or filtered group, use the Random Recipient Selection criteria. These criteria select a random group of subscribers from the larger group you’re applying Random Recipient Selection to. That is, if the only filtering criteria you’re using is Random Recipient Selection, you’ll be filtering a random number of subscribers from your topic for your new recipient list. If other filtering criteria exist for this topic, the Random Recipient Selection criteria selects a random number of subscribers from that filtered subset.
For example, an administrator wants to send a bulletin to a random set of topic subscribers who haven’t opened a specific bulletin sent from her office. To do so, in the Recipients pane of her bulletin, she selects the topic, and then adds two filtering criteria. First she used the Open Activity criteria, defining it as “Subscribers who did not open the bulletin: September 22 test 2.” Next, she set the Random Recipient Selection to “Randomly select 15 percent of selected subscribers.”
In this example, the Random Recipient Selection criteria were applied to the subset of the topic’s subscribers who didn't open the topic bulletins sent out on September 22.