The Estimated audience size under Rules displays an estimate of how many users are in a specific audience. It returns the number of shoppers that match any or all of the rules depending on the current value of the Rule Matching selection list, and it rounds the result to the nearest multiple of 10 users. In a multiple-site environment, the audience size is estimated for the default site.
Each successive rule shows the new size of the audience with that rule added.
For Match Any Rule, each successive rule adds just those shoppers who satisfy that rule but did not satisfy any of the previous ones. The audience can only grow or stay the same size as rules are added, and each new size shows that growth.
For Match All Rules, each successive rule adds a new restriction to the audience, removing shoppers who satisfied the previous rules but do not satisfy the new one. The audience can only decrease or stay the same size as rules are added, and each new size shows that decrease.
Note:
Changing the order of the rules affects the size estimates per rule on the Audiences page, but does not affect the audience size and shoppers evaluated as being members of the audience. To see the accurate size of a rule on the Audiences page, create an audience with only that rule.