Incrementality exercises produce fragile excitement. The memo matters as much as the math. Lead with the question you set out to answer, then list assumptions that would flip the conclusion. Partners respond better when uncertainty is front-loaded instead of buried in footnotes.
Use a dissent box: verbatim quotes from channel leads who disagree, plus your response or acknowledgment. If you cannot fill the dissent box, you have not talked to enough stakeholders. Pair quantitative bands with qualitative launch notes—numbers without calendar context invite myth-making.
When evidence is thin, say so plainly and propose the next measurement action. Pausing a narrative is a strength, not a failure. Teams that pause cleanly rebuild trust faster than teams that ship heroic charts.