---
title: When last-click attribution is good enough (and when to invest in incrementality)
slug: when-last-click-is-good-enough
summary: For small, performance-driven advertisers on one or two channels, last-touch attribution is often ~85% as good as experiments and better than a bad MMM; invest in incrementality tests as spend, channel count and brand effects grow.
domain: marketing
tags: [measurement, attribution, incrementality, mmm, small-budget]
related: [measurement-stack-attribution-incrementality-mmm, last-click-attribution-biases, incrementality-test-design, mmm-evaluation-and-open-source, apple-ads-attribution-without-mmp]
sources: [yt:tJzzjP29f-k, yt:3Uj6p1N8VJA, yt:qZj6_mJGOMg]
updated: 2026-10-24
---

# When last-click attribution is good enough

## TL;DR
- Kaminsky (an MMM vendor) argues most businesses don't need an MMM, and that an average MMM is net-negative because it actively misleads.
- One study he cites found last-touch about **85% as good** as running only incrementality experiments.
- Use common sense. At your first dollars, or with nearly all spend on one channel, there are few competing claims for each conversion.
- Escalate when spend is big and mixed. Run a geo test and ask how far off last-click is: about 5% means move on; over 20% means dig in.
- Fewer channels make measurement easier. One veteran gaming UA lead keeps small budgets on 1–2 channels partly for this reason.

## Details
**Last-touch is underrated for small advertisers.** [[people/michael-kaminsky]] says last-touch "has lots of problems", but for small, performance-marketing-driven businesses it often works well, and an MMM would do worse.[^1] He cites recent studies finding last-touch about 85% as good as only doing incrementality experiments. In small businesses he works with, more Facebook/Google spend visibly produces more conversions in the raw data, and that lines up with last-touch.[^2] Last-touch starts to fail with complex mixes and much larger budgets.[^2]

**The common-sense dimension** ([[people/eric-seufert]]). If you're spending your first dollar on digital ads, causality isn't your problem. Misattribution becomes realistic as you add word of mouth, a brand, loyal customers and several digital channels running at once.[^3] Kaminsky: a business spending $1M/month mostly on Facebook is probably close to 100% incremental, with little baseline. A test there exists to size the error. Off by 5%? It probably doesn't matter. More than 20%? Dig in.[^4] Seufert stresses this is a scale question, not an argument against incrementality testing.[^5]

**Keep the mix narrow early.** [[people/nebojsa-radovic]] (Zynga) tells six-figure-a-month game advertisers to run just Google on Android and AppLovin on iOS, and do them well. Measurement becomes "really, really easy" with one channel per platform.[^6]

**Signals that last-click is no longer enough:**
- Several channels compete for the same users, especially search plus social plus video.
- Spend moves into view-based channels (YouTube, CTV, chatbot ads) that last-click can't see.[^7]
- Channel ROAS looks fine but the top line doesn't move when you scale.

## Disagreements / caveats
- [[people/olivia-kory]] (Haus) reports cases where last-click ranks channels in the *reverse* order of incrementality (Google UAC standard vs video). See [[last-click-attribution-biases]]. Even a "good enough" last-click can misallocate between channels.
- The 85% figure is one study Kaminsky mentioned from memory, not a benchmark to rely on.

## See also
- [[apple-ads-attribution-without-mmp]] — weekly spend-vs-revenue for a 1–2 channel setup
- [[incrementality-test-design]]

[^1]: yt:tJzzjP29f-k @ 14:24 — Michael Kaminsky
[^2]: yt:tJzzjP29f-k @ 15:17 — Michael Kaminsky
[^3]: yt:tJzzjP29f-k @ 17:40 — Eric Seufert
[^4]: yt:tJzzjP29f-k @ 18:29 — Michael Kaminsky
[^5]: yt:tJzzjP29f-k @ 20:05 — Eric Seufert
[^6]: yt:3Uj6p1N8VJA @ 42:10 — Nebojsa Radovic
[^7]: yt:qZj6_mJGOMg @ 22:17 — Olivia Kory