The unique number of users who have taken any one of your selected MAE Score acts of engagement in the previous period but haven’t joined the group. The previous period is the same span of dates immediately before your report period. If you are filtered to the last 7 days then the previous period is the 7 days prior to the last date of your current period. For example March 25th – March 31st. Previous period would be March 18th to March 24th.