Level: Intermediate
As budget increases on a fixed audience, cost per result typically rises, since additional spend reaches progressively less responsive segments of that audience.
Plot Spend Against CPA to See the Curve
Charting daily or weekly spend against resulting CPA across a range of budget levels reveals the point where efficiency starts declining.
Identify Your Efficient Scaling Range
Most campaigns have a range of spend where CPA stays relatively stable before climbing noticeably — knowing that range prevents scaling past the point of real efficiency.
Expand Audience Size to Push the Curve Further
Broadening targeting or adding new audience segments can extend the range of efficient scaling, since it introduces new, unsaturated audience to reach.
Next step: Use the Sales Letter Writer to recognize that stronger creative can also shift the diminishing-returns curve favorably, since more persuasive copy converts a larger share of an increasingly less-responsive audience than weaker copy would.