Unlike the way that charities traditionally select their lists, Dataro does not use an 'active universe' of recent donors. Instead, our analysis goes back as far as your database does, and we examine the patterns of giving to generate individual predictions for every donor.
Of course, certain factors such as more recent giving are going to influence who gets selected for a campaign list, but by limiting yourself to an active universe of say 12 or 24 months, charities are missing out on a sizeable number of potential donations from other parts of their database, including 'lapsed' givers.
Understandably, the reason charities used an active universe in the past is because they were not able to easily tell which of the longer lapsed givers was likely to give, and contacting the whole cohort was not cost effective. However, now that you can now identify which individuals (rather than segments) are more likely to give, we believe that propensity scores will supersede the active universe concept.