Last-click attribution

Last-click attribution assigns 100% of the credit for a conversion to the most recent touchpoint a customer interacted with before converting, ignoring every earlier ad, email, or organic visit in that customer's path. It is the default model in most analytics platforms because it is simple to compute and does not require modeling a whole journey.

The calculation just looks up the last recorded click or session within the attribution window and gives it the full conversion. This differs from first-click attribution, which credits the opening touchpoint instead, and from data-driven attribution or other multi-touch attribution models, which split credit across several touchpoints based on their actual contribution.

Last-click attribution systematically overvalues bottom-of-funnel channels, branded search and retargeting in particular, because they tend to be the last thing a person clicks regardless of what actually persuaded them earlier. It undervalues awareness and consideration channels that start the journey but rarely close it. Practitioners still use it for its simplicity and consistency across time, but pairing it with a multi-touch or incrementality-based model is standard practice before shifting budget between channels based on it alone.