Time-Decay Attribution.

Time-decay attribution is a multi-touch attribution model that distributes conversion credit across all touchpoints in the customer journey, but assigns more credit to touchpoints that occurred closer to the conversion event. It is based on the assumption that marketing interactions closer to the purchase decision have a stronger influence than those that happened weeks or months earlier — hence 'time-decay': the further from conversion, the less credit the touchpoint receives.

Time-Decay vs Other Attribution Models

Last-click gives 100% credit to the final touchpoint. First-click gives 100% to the first. Linear gives equal credit across all touchpoints. Time-decay is a compromise: it acknowledges that multiple touchpoints contributed, but weights recency as a proxy for causal impact. Position-based (U-shaped) attribution gives extra credit to the first and last touch, and distributes the remainder among the middle. Data-driven attribution uses machine learning to assign credit based on actual conversion probability uplift.

Limitations and When to Use

Time-decay undervalues top-of-funnel channels like organic search and brand content that introduce prospects to a brand early in a long consideration cycle. A user who discovered a SaaS tool through an organic blog post six months ago, then converted after clicking a retargeting ad yesterday, would see the blog post receive almost no credit in a time-decay model — despite its role in initiating the relationship. For long B2B sales cycles, position-based or data-driven attribution typically provides a fairer picture.