Here's a question that comes up a lot in marketing teams that are trying to get more sophisticated about measurement: should we invest in multi-touch attribution, or run incrementality tests?
The short answer is that they answer completely different questions. And understanding which question you're actually trying to answer makes the choice obvious.
Multi-touch attribution: the detailed view
Multi-touch attribution (MTA) tries to track an individual user across their entire journey and give credit to each touchpoint they had along the way. The Instagram ad they saw but didn't click, the email they opened two days later, the blog post they read, the branded Google search they did right before buying — MTA tries to assign a piece of the credit to each of those interactions.
The upside is granularity. You can see which specific creatives, emails, or content pieces are involved in conversions. You can see which channels assist versus close.
The downside is that MTA relies on being able to track individuals, which requires cookies, device fingerprinting, or some form of persistent identifier. As privacy regulations tighten and browsers block more tracking, MTA data gets noisier and less reliable. You're getting a detailed picture of an incomplete dataset.
Incrementality testing: the proof test
Incrementality testing (sometimes called lift testing) takes a completely different approach. Instead of tracking individual users, you run a controlled experiment.
You divide your market into two groups. One group sees your ads (or email campaign, or whatever you're testing). The other group is a "holdout" — they don't see anything. After the test period, you compare conversion rates between the two groups. The difference is the incremental lift your marketing actually caused.
The upside: this approach doesn't care about cookies or tracking. It measures actual causal impact — did this channel cause more sales to happen? — not just correlation.
The downside: it's slow, requires pausing campaigns to create holdout groups, and you need sufficient volume for statistical significance. You can't run one of these every week.
How most teams use both
Day-to-day campaign optimization benefits from MTA. Even imperfect MTA data helps you understand which creatives are working and which channels are contributing to the funnel. As long as you're using server-side link tracking to maximize data quality, MTA gives you useful directional signals.
Incrementality tests are for strategic calibration — running quarterly or biannually on major channels to answer the big question: "Would these sales have happened anyway, even without the ads?" If an incrementality test shows your Facebook campaigns have zero lift, that's a conversation-changer regardless of what MTA says.
Use MTA for the day-to-day. Use incrementality tests to sanity-check your assumptions about which channels are actually moving the needle.
For the best MTA foundation possible, all your links need to be tracked server-side. gometrify captures every click independently of browser cookies — which means cleaner MTA data to feed into your models. Start tracking every touchpoint →