What drop-off tells you
Drop-off is the share of people lost at each step of the journey after a scan. Every step loses some people; measuring where the losses concentrate tells you which step to fix first.Some drop-off is healthy. People who were never going to convert should leave early rather than waste support time later.
How to compute drop-off
Drop-off at a step = people who entered the step minus people who completed it, divided by people who entered, multiplied by 100.Illustrative example numbers, not real-world data: 120 people start a form and 60 complete it, giving (120 - 60) / 120 x 100 = 50% drop-off at the form step. Halving that drop-off would add 30 completions without a single extra scan.
How to collect the data
Instrument each step of the journey, from scan to confirmation, and count one cohort through all steps in the same period.Keep the raw counts, not just the final percentage. Raw counts let you recompute the metric if you later fix the definition, and they make it possible to spot a denominator problem, such as a week where exposures were estimated instead of counted. Store the counts in one place with the date range, the placements included, and the name of the person who pulled them. That small discipline turns a spreadsheet into an audit trail.
Reading the result
Never judge drop-off as a single number. Break it down by form step, page, device, and placement. A campaign that looks average overall may be strong in one segment and weak in another, and the fix is completely different in each case. Compare the same placement against its own past, and compare different placements only when their audiences and contexts are genuinely similar. A short trend over four or more comparable periods is worth far more than a single snapshot, because it separates a real shift from weekly noise.Also check the relationship between drop-off and the metrics around it. If scans rise while conversions fall, the new scanners may be less interested visitors, or the landing page may have changed. If cost rises while drop-off stays flat, you are paying more for the same outcome. Metrics make sense in groups, not in isolation, and the habit of reading two or three together prevents most misreadings.