Decay Model
An attribution approach that assigns decreasing credit to touchpoints based on their distance in time from the conversion event, giving more weight to recent interactions and less to earlier ones.
Also known as: time decay model, time decay attribution
Why It Matters
Decay models reflect a common-sense intuition: the closer an interaction is to the moment of conversion, the more likely it influenced the decision. A product demo three days before purchase probably had more impact than a blog post read six weeks ago.
This approach offers a middle ground between the extremes of first-touch attribution (which ignores recent interactions) and last-touch attribution (which ignores everything that came before). Decay models acknowledge the full journey while recognizing that recency matters.
Decay models are particularly well-suited for businesses with considered purchases where multiple touchpoints happen over days or weeks. The model naturally adapts to different journey lengths - a quick purchase gives most credit to the few recent touchpoints, while a long evaluation distributes credit more evenly because even the "recent" touches span a longer period.
How to Calculate
In a time decay model, each touchpoint receives credit based on an exponential decay function. A common approach uses a half-life parameter: touchpoints at the half-life point receive 50% of the credit of the most recent touchpoint, touchpoints at 2x the half-life receive 25%, and so on. All credits are then normalized so they sum to 100% of the conversion value.
Industry Applications
A luxury skincare brand uses a 7-day half-life decay model and discovers that email retargeting receives 35% of conversion credit while influencer content - which happens earlier in the journey - receives only 10%. They test pausing influencer spend and see conversions drop, revealing that the decay model undervalues early awareness.
A marketing automation platform uses a 14-day half-life and finds that sales demo calls receive the most credit (occurring close to conversion), while content downloads and webinars receive less. The model validates their investment in sales-assisted conversion for enterprise deals.
How to Track in KISSmetrics
Configure time decay attribution in KISSmetrics by selecting the decay model in your attribution settings. Choose a half-life that matches your business - 7 days for fast sales cycles, 14-30 days for longer ones. Use the Attribution Report to see how credit distributes across channels and campaigns under the decay model.
Common Mistakes
- -Using a half-life that does not match your actual sales cycle, which either over-credits or under-credits early touchpoints
- -Assuming decay models are always better than simpler models without testing whether the added complexity improves decisions
- -Not comparing decay model results against other models to understand how much your channel rankings change
- -Applying decay models to awareness-stage metrics where the goal is brand building, not direct conversion
Pro Tips
- +Test multiple half-life settings (7-day, 14-day, 30-day) and see which one produces channel rankings that best predict future conversion rates
- +Use decay models alongside linear and position-based models to triangulate the true value of each channel
- +Apply steeper decay curves for impulse-purchase products and gentler curves for high-consideration purchases
- +Remember that decay models still undervalue true top-of-funnel channels - complement with incrementality testing for a full picture
Related Terms
Time-Decay Attribution
A multi-touch attribution model that assigns increasing credit to touchpoints closer to the conversion event, based on the assumption that more recent interactions had greater influence on the purchase decision.
Attribution Model
A set of rules or algorithms that determine how credit for conversions and revenue is assigned to the marketing touchpoints in a customer's journey, shaping how channel ROI is measured and budget is allocated.
Multi-Touch Attribution
An attribution approach that distributes conversion credit across multiple touchpoints in a customer's journey rather than assigning all credit to a single interaction, reflecting the reality that most conversions involve multiple marketing influences.
Linear Attribution
A multi-touch attribution model that distributes conversion credit equally across every touchpoint in the customer journey, giving the same weight to the first, middle, and last interactions.
Position-Based Attribution
A multi-touch attribution model that assigns the most credit to the first and last touchpoints in the customer journey (typically 40% each) while distributing the remaining credit equally among middle interactions.
See Decay Model in action
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