Definition:
Incrementality is a measurement framework that isolates the additional performance lift produced by a specific marketing action, budget change, or operational decision - beyond what would have occurred in its absence. It is typically evaluated through controlled tests (holdout groups, geo-splits, or pre/post comparisons with matched cohorts) that make it possible to attribute performance changes to a specific variable rather than external market conditions or overlapping initiatives.
Why it matters:
Attribution models tell you which channels receive credit; incrementality tells you which channels actually caused results. This distinction matters enormously in multifamily, where seasonal demand, rent pricing changes, and competitive openings can produce occupancy swings that have nothing to do with marketing activity. Without incrementality measurement, it is easy to over-invest in channels that appear to convert well simply because they intercept high-intent traffic, rather than creating it. Incrementality testing is also valuable for evaluating vendor changes, budget shifts, and new campaign formats, giving operators an evidence-based foundation for decisions that are often made on intuition or insufficient data.
