What is the difference between incrementality and attribution in CTV?

Two different questions

Attribution asks: "Of the households that saw the ad, how many converted?" Incrementality asks: "How many more conversions happened because of the ad than would have happened without it?" The difference is the counterfactual: a group that did not see the ad.

An example makes the gap clear. Suppose 10,000 exposed households produce 300 purchases in a week. Attribution reports 300. If a matched group of 10,000 unexposed households produced 240 purchases in the same week, the incremental effect is 60 purchases. The ad added 60, not 300.

How incrementality is measured

There are three common designs.

1. Holdout groups. A random share of the target audience is withheld from the campaign. Comparing the two groups estimates the lift.
2. Geo holdouts (geo experiments). Whole regions are switched on or off. Sales in test regions are compared with matched control regions. This works even when user-level matching is limited. The next lesson walks through one.
3. Modelled approaches. Marketing mix models (MMM) and incrementality-adjusted attribution estimate lift from historical patterns and spend variation, without a dedicated holdout.

What platforms publish

Several platforms described incrementality on their own pages:

• Vibe's MCP page states "incrementality testing built in", with example geo holdout and cross-channel lift prompts. Its integrations page names Haus and Prescient among measurement partners.
• tvScientific describes "Incrementality-driven attribution" and "incremental lift analysis".
• Tatari states it can "Measure the true incremental impact" of TV.
• StackAdapt lists brand lift, sales lift and store visit measurement.

Other platforms in our ranking did not describe incrementality or lift testing on the pages we read. That does not mean they cannot run one; it means a buyer should ask.

Why incrementality matters more for CTV

CTV campaigns often target audiences that overlap with existing customers, and the effect of a TV ad can arrive days later through search or direct visits. Both inflate attribution. A lift test is the clearest way to separate the ad's effect from background demand, and it is the evidence finance teams tend to accept.

Costs of testing

A holdout test withholds media from some households or regions, so part of the potential reach is deliberately unused. Tests also need enough volume to detect a difference; a small budget over a short period may produce a result too noisy to act on. Plan the test size before launch.

How this shows up in our scores

Incrementality and lift testing carries 20% of our weight, the same as outcome measurement. Together they make up 40%, because the lead question of our ranking is about proving results.