Reach is the most quoted metric in advertising — and one of the most misunderstood. The version most reports use isn't the version that should drive a decision.
Why raw platform reach can mislead
Each platform reports its own delivery in good faith. The problem is what happens when you add them up: the same person can be counted across multiple platforms, and the total inflates.
What deduplicated means in plain English
Deduplicated reach is the unique number of people reached after overlap across media is removed. It is, simply, the number you'd want if you were briefing the CEO.
Why overlap matters more than headline numbers
Overlap is not a detail. It tells you which channels are adding new audiences and which are repeating exposure. That's the real strategic question.