Attribution (digital marketing)
Attribution determines which marketing interaction(s) contributed to a conversion. Models range from last-click (all credit to the last channel) to data-driven (algorithmic distribution based on actual conversion history), each painting a different picture of channel value.
In practice
GA4 uses the data-driven model by default when data is sufficient, or last non-direct click otherwise. The last-click model overestimates SEO and transactional emails because they often appear at the end of the journey. A linear or position-based model gives a fairer view of SEO’s contribution in long purchase cycles. Comparing multiple models in GA4 reveals underestimated channels.