Position-Based Attribution (U-Shaped)

Take the touchpoints recorded for a person inside the attribution window, then apply the split.

1. The first recorded touchpoint gets 40%.
2. The last touchpoint before the conversion gets 40%.
3. The remaining 20% is divided equally among all touchpoints between them.
4. A journey with only two touches splits 50/50; a journey with one touch gets 100%. There is no middle to fund.

The 40/40/20 split is a convention rather than a law. Google's rule-based position-based model used exactly those numbers, and most attribution tools ship them as the default; some let you change the weights, which turns the model into a family rather than a single rule.

The same journey used across these entries: a €12,000 deal, four recorded touches over three weeks, the deal closing five weeks after the form.

• Day 1: Meta ad clickDownloads a guide from a Meta lead campaign. First touch, 40%. Credit: €4,800.
• Day 8: Google Search adClicks a generic search ad and reads the pricing page. Middle touch, half of the 20%. Credit: €1,200.
• Day 15: newsletter clickClicks through to a case study from the nurture email. Middle touch, half of the 20%. Credit: €1,200.
• Day 22: brand search ad, form fillSearches the company name, clicks the brand ad and books a demo. Last touch, 40%. Credit: €4,800.

Meta and brand search each report €4,800, the two middle touches €1,200 each. Compared with last-click, brand search gives up 60% of the deal; compared with first-click, Meta does the same. The middle gets something without getting much, which is roughly how most marketers already think about nurture.

• Discovery is a real event

  Somebody had to introduce the company. The first touch is the only one that could not have been retargeting, so it carries information no later touch does.

• Decision is a real event

  The last touch is where intent became action. It is also what the sales team sees, and what the CRM stamps as lead source.

• The middle is long and quiet

  Nurture emails, retargeting, a second blog post. Each one probably helped and none of them was decisive, so a small shared pot matches what most teams believe about them.

B2B attribution vendors extended the idea from the ends of a session list to the stages of a pipeline. The variants differ in how many milestones they anchor on.

• U-shaped (position-based)

  Two anchors: first touch and lead conversion, 40% each, 20% in between. The model this page is about.

• W-shaped

  Three anchors: first touch, lead creation and opportunity creation, 30% each, the remaining 10% shared by the touches in between. Built for teams whose CRM records an opportunity stage.

• Full-path

  Four anchors: first touch, lead creation, opportunity creation and closed-won, 22.5% each, 10% for everything else. Popularised by Bizible, and only usable when the CRM writes every stage back to the journey.

The further down that list you go, the more the model depends on the CRM: the anchors are pipeline stages, not clicks, so the journey has to be joined to the deal record. That join is the whole job of multi-touch attribution software, and it is why these models are rare outside B2B.

• The first touch is only the first you recordedIf the real first visit is outside your storage window or on another phone, 40% goes to whatever was recorded first, which is often a retargeting click or a brand search. The model then rewards the closer twice.
• The middle can be starved20% across eight nurture touches is 2.5% each. A long, content-heavy journey gets the same middle pot as a short one, so nurture spend looks smaller the better the nurture works.
• The weights are a belief40/40/20 was never derived from data; it was a reasonable guess that stuck. It is a good default and a poor argument, and data-driven models exist because someone wanted to check.
• Platforms no longer report itGoogle removed position-based from Google Ads and GA4 in 2023 along with the other rule-based models. If you want a U-shaped view of paid media, it has to be built from your own journey data.

Position-based attribution is the model most B2B teams settle on because it matches how they already think: someone found the customer, someone closed them, and the middle helped. The 40/40/20 split is a convention, not a finding, so treat it as a sensible default rather than a truth, and make sure the 'first' touch it credits is the real one. The overview of every model on the same example is under attribution model, and marketing attribution software is what makes the journeys long enough to split at all.