---
title: "What is incrementality?"
description: "Incrementality is revenue the campaign caused that would not have happened anyway. You measure it by comparing treated accounts against a holdout."
canonical: https://trysincerely.com/glossary/incrementality
last_updated: 2026-09-18
---
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# What is incrementality?

> Incrementality is revenue the campaign caused that would not have happened anyway. You measure it by comparing treated accounts against a holdout.

Source: https://trysincerely.com/glossary/incrementality

Incrementality is the outcome a campaign caused, not just the outcome it touched. It answers one question: how many of these conversions would have happened anyway? You measure it by comparing accounts that got the campaign against a similar group that did not.

## Why it matters

Attribution counts credit. Incrementality counts cause. A mailer can "influence" 40 deals that were already going to close, and attribution will happily claim all 40. Incrementality strips that out, so you only pay for outcomes the campaign actually created.

This matters most in B2B, where your best accounts get hit by every channel at once. Without an incrementality read, direct mail either gets over-credited (it landed on accounts sales was already working) or under-credited (it warmed accounts that later converted through email). The fix is the same in both cases: hold back a random slice of the audience, mail the rest, and compare. The difference is your [lift](https://trysincerely.com/glossary/lift), and the held-back group is your [holdout](https://trysincerely.com/glossary/holdout).

Sincerely locks this design at campaign launch: primary outcome, measurement window, and holdout percentage. Readouts report lift with confidence intervals and say plainly when a result is not statistically ready.

## Example

You have 1,000 target accounts. You mail 900 and hold out 100 at random. After 60 days, 45 mailed accounts book a meeting (5%) versus 3 holdout accounts (3%). The incremental effect is 2 percentage points: roughly 18 of those 45 meetings happened because of the mail. Attribution would have claimed all 45.

Whether 2 points is real signal or noise depends on sample size. See [minimum detectable effect](https://trysincerely.com/glossary/minimum-detectable-effect), or run the numbers in the free [lift-significance calculator](https://trysincerely.com/tools).

Incrementality is the only number that tells you whether to run the campaign again.

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Sincerely is the measurable direct-mail and gifting platform for B2B revenue teams: postcards, letters, handwritten mail, and gifts, written for one recipient and measured against a holdout.

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