--- title: Position-Based Attribution Explained | Attribution Model Guide | RGM® url: https://realgrowthmatters.com/learn/measurement/position-based-attribution/ updated: 2026-06-10 source_html: https://realgrowthmatters.com/learn/measurement/position-based-attribution/ --- # Position-Based Attribution: 40 percent to first, 40 percent to last, 20 percent to the middle. Position-based (U-shaped) attribution gives 40 percent of conversion credit to the first touch, 40 percent to the last, and 20 percent split among the middle touches. Acknowledges that both endpoints of the journey matter. Part of the attribution model family that also includes first-touch, last-touch, linear, time-decay, position-based, Markov chain, and Shapley attribution. Modern teams use multiple models in parallel and validate against incrementality testing. By **David Schaefer** · [LinkedIn](https://www.linkedin.com/in/daschaefer/) · Updated May 2026 · 10 min read · [5 sources cited](#sources) ## Key takeaways - Position-based attribution gives 40 percent to first touch, 40 percent to last touch, 20 percent split among middle touches. - Also called U-shaped attribution. The terms are interchangeable. - Acknowledges that both endpoints of the journey usually matter most while keeping middle touches in the model. - W-shaped variant adds a third bucket for an opportunity-creation milestone in long B2B journeys. - Right for journeys where both awareness and closing matter. Wrong for pure direct-response or pure awareness campaigns. - The 40-20-40 split is convention, not science. Customize based on your funnel data. ## What position-based attribution is Position-based attribution — also called U-shaped attribution — gives 40 percent of conversion credit to the first touchpoint, 40 percent to the last, and 20 percent divided equally among the middle touches. The model assumes that the channel that introduced the customer and the channel that closed them both deserve disproportionate credit, while the supporting touches in between get less. Google Analytics offered position-based as a built-in model for years before the data-driven default switch in 2023. The model exists as a compromise between first-touch (100 percent to first), last-touch (100 percent to last), and linear (equal credit to all). It says both endpoints matter, the middle still counts, but the middle counts less. The 40-20-40 split is the standard but the percentages are configurable. ## How it works Track every touchpoint in the journey. Identify the first and last touches; give each 40 percent of the conversion credit. Divide the remaining 20 percent equally among the middle touches. A two-touch journey gets 50-50 split (since there is no middle). A three-touch journey gets 40-20-40. Five touches gets 40-5-5-5-5-40. ## When position-based attribution fits Position-based fits journeys where both awareness (first touch) and closing (last touch) clearly matter, with supporting touches in between. Most B2B and high-consideration B2C journeys fit this shape. The model is wrong for true direct-response campaigns (where closing is everything) and for pure awareness campaigns (where the first touch is everything). The W-shaped variant adds a third bucket for "opportunity creation" or "lead qualification" touches in the middle, giving them additional credit. Used in long B2B journeys where multiple meaningful milestones exist between first touch and conversion. ## Common failure modes Two failures. Treating the 40-20-40 split as universal when the actual journey shape varies. Comparing position-based to last-touch without recognizing the structural difference. **Universal split.** The 40-20-40 default assumes both endpoints matter equally. For some businesses, first-touch matters far more (brand-led B2C); for others, last-touch dominates (retargeting-heavy DTC). The fix is to either adjust the split based on data or use multiple models in parallel. **Comparing across models.** A channel with low last-touch credit and high position-based credit often appears early in journeys but does not close. The interpretation depends on the channel type. Awareness channels frequently show this pattern; closing channels with this pattern are usually being optimized incorrectly. ## Quick answers What is position-based attribution? : 40 percent of conversion credit to the first touch, 40 percent to the last, 20 percent split among the middle. Acknowledges both endpoints matter. Why 40-20-40 specifically? : Convention, not science. The split says both endpoints carry weight; the middle still counts but less. Other splits are configurable. Is position-based the same as U-shaped? : Yes. The terms are interchangeable. What is W-shaped attribution? : An extension that adds a third bucket for an opportunity-creation or lead-qualification milestone in the middle of long B2B journeys. When does position-based fit? : Journeys where both awareness and closing matter, with supporting touches between. Most B2B and high-consideration B2C. When is it wrong? : Pure direct-response campaigns (closing dominates) and pure awareness campaigns (first touch dominates). ## Frequently asked What is position-based attribution? Also called U-shaped attribution. Gives 40 percent of conversion credit to the first touchpoint, 40 percent to the last, and 20 percent divided equally among the middle touches. The model acknowledges that both endpoints of the journey usually matter most. Where did the 40-20-40 split come from? Convention rather than empirical research. The split is configurable; the standard 40-20-40 represents 'both endpoints matter equally' as a default assumption. Some implementations use 30-40-30 or other variants. What is W-shaped attribution? An extension of position-based that adds a third bucket for an opportunity-creation or lead-qualification milestone in the middle. Used in long B2B journeys where multiple meaningful intermediate stages exist. When is position-based the right model? Journeys where both awareness (first touch) and closing (last touch) clearly matter, with supporting touches in between. Most B2B and high-consideration B2C journeys fit this shape. When is position-based wrong? Pure direct-response campaigns where closing is everything. Pure awareness campaigns where first touch is everything. Very short journeys (two touches or fewer) where the model degenerates to 50-50. How is position-based different from linear? Linear gives equal credit to every touch. Position-based weights endpoints more heavily (40 percent each) and middles less (20 percent total split). Position-based is a stronger structural assumption. How is position-based different from data-driven? Position-based uses a fixed rule (40-20-40). Data-driven uses observed user paths to estimate each channel's contribution probabilistically. Data-driven is closer to causal but requires substantial data volume. Can I customize the position-based split? Yes. Most attribution tools let you adjust the percentages. Common alternatives: 50-25-25 (last-touch heavy), 30-40-30 (middle-touch emphasized), or W-shaped for long journeys. ### Sources cited on this page 1. Google — [Attribution models documentation in GA4](https://support.google.com/analytics/). 2. Avinash Kaushik — [Occam's Razor blog on attribution models](https://www.kaushik.net/avinash/). 3. Anderl, Becker, von Wangenheim, Schumann — "Mapping the Customer Journey", International Journal of Research in Marketing (2014). 4. Anthropic / Google AI — Academic literature on attribution modeling. 5. Real Growth Matters Inc. — Internal audit data on attribution-model performance, 2024-2026.