The cheapest revenue you're not earning.

Four numbers, multiplied

Factor	Where it comes from
Patients coming due per week	Your answer — midpoint of the range you pick
× estimated lapse rate	Conservative lookup keyed to your Recall Score — weaker recall, more patients drift
× rebook rate when properly recalled	Conservative working assumption (a quarter to a third — these people already chose you once)
× value of one returning visit	Your answer, including what a visit typically leads to

A dental practice with 42 patients due weekly, a score in the "Leaking" band (35% estimated lapse), a 30% rebook rate and a $750 returning-visit value: 42 × 4.3 × 35% × 30% × $750 ≈ $14,000 a month in patients who would have come back if asked properly. And unlike new-patient marketing, every dollar of it arrives without ad spend.

Estimates from your own answers using stated assumptions — labeled that way in every report. The measured discovery maps the recall flow that produces your real rate.

The compounding version

A patient recalled on time this year is a patient still active next year — recall protects the whole future stream, not one visit. A patient who lapses un-asked doesn't just miss one cleaning; they quietly exit the lifetime relationship, and reacquiring them later (if a competitor doesn't first) costs marketing money you never needed to spend. The quiet file grows in one direction unless something systematically works it.