What Is Time-Decay Attribution?
Time-decay attribution is one of the core multi-touch attribution models used in digital marketing. Rather than awarding all conversion credit to a single touchpoint, it distributes credit across every channel a customer engaged with on their path to converting. The key principle is temporal weighting: the closer a touchpoint is to the actual conversion moment, the more credit it receives.
The model uses an exponential decay function. If a customer clicked a Google Ad seven days before converting, viewed an organic search result three days before, and then clicked a remarketing ad on the day of purchase, the remarketing ad would receive the largest share of credit, the organic visit a moderate share, and the initial Google Ad the smallest share. The exact weight depends on the half-life period you configure in your analytics platform, commonly set to seven days in Google Analytics 4.
This model operates on the logical assumption that a customer who interacted with your brand yesterday is more likely to have been influenced by that interaction than by something they saw a month ago. It reflects how purchasing intent typically builds and peaks just before a decision is made. For South African businesses running short promotional windows, such as Black Friday campaigns or end-of-month salary-day specials, time-decay attribution often produces the most intuitive and actionable credit distribution of all rule-based models.
Unlike position-based attribution, which places particular emphasis on the first and last touches, time-decay treats the journey more holistically while still acknowledging that recency matters. It is especially popular with teams managing paid search, retargeting, and email automation, where the closing interactions are often the easiest to track and justify to finance teams.
Time-Decay Attribution In Practice
Imagine a Johannesburg-based furniture retailer running a multi-channel campaign across Google Search, Facebook retargeting, and email. A customer discovers the brand through a Facebook video ad two weeks before month-end. Over the following days, they click a Google Search ad, browse the product page, and then respond to an email newsletter on payday. They complete the purchase after clicking a remarketing banner the following morning.
Under time-decay attribution, the remarketing banner and the email newsletter receive the highest credit because they occurred within 24 to 48 hours of the purchase. The Google Search ad gets moderate credit, and the initial Facebook video ad receives the least. This immediately signals to the marketing team that the lower-funnel retargeting spend and email list are producing the most direct value in the closing window. Budget decisions for the next campaign can be made with that data in hand, rather than guessing which channel matters most. For businesses spending tens of thousands of rand each month on paid media, these insights translate directly into better return on ad spend and more efficient campaign structures.
How time-decay attribution works
Time-decay attribution is an attribution model that gives more credit to the touchpoints closer in time to the conversion, and progressively less to earlier ones. Rather than crediting all touches equally (linear) or emphasising the first and last (position-based), time-decay assumes that interactions nearer the moment of conversion were more influential in the decision, so the last touch gets the most credit, the one before it somewhat less, and so on back through the journey, with the earliest touches receiving the least. The credit decays as touchpoints recede into the past, hence the name. This reflects a view that recent interactions weighed most heavily on the decision to convert, which suits situations where the buying process is relatively short or where later engagement is genuinely more decisive. It still recognises the whole journey, crediting every touch, but weights it towards the recent end, offering a middle ground between last-click attribution, which ignores all but the final touch, and models that treat earlier touches as equally or more important.
When to use time-decay attribution
Time-decay attribution suits businesses whose buying journeys are relatively short, or where recent interactions genuinely drive the decision more than early ones, so weighting credit towards the touches nearest conversion reflects reality. It improves on last-click attribution by still crediting the earlier touchpoints that contributed, while acknowledging, unlike linear attribution, that not all touches are equally influential and recency matters. Its assumption, that closer-in-time means more influential, is a simplification that does not fit every case: for some products a pivotal early introduction or a key mid-journey moment matters as much as recent touches, which time-decay under-credits, and for long consideration cycles the emphasis on recency may distort the picture. As with all rule-based models, it applies a fixed assumption uniformly, whereas data-driven attribution assigns credit from actual data. Time-decay is best chosen deliberately when you believe recent interactions are genuinely more decisive for your customers, offering a sensible, transparent weighting for shorter or recency-driven journeys, rather than as a default without considering whether its recency assumption fits how your customers actually decide.
FAQ
When should I use time-decay attribution?
Time-decay attribution works well for short sales cycles where recent interactions carry the most buying intent. It suits e-commerce businesses and promotions with tight windows. Businesses running flash sales or time-limited campaigns in South Africa often find this model reflects their conversion patterns accurately.
How does time-decay differ from last-click attribution?
Last-click gives 100 percent of credit to the final touchpoint and ignores all prior interactions. Time-decay spreads credit across all touchpoints but weights recent ones more heavily. This gives upper-funnel channels some recognition while still favouring the channels that closed the sale.
When should you use time-decay attribution?
When buying journeys are relatively short, or when recent interactions genuinely drive the decision more than early ones, so weighting credit towards the touches nearest conversion reflects reality. It suits recency-driven paths; for journeys where an early introduction or mid-point is pivotal, its recency emphasis under-credits those, so consider whether the assumption fits your customers.