Attribution Models – Explained

Most customers will follow the standard purchase funnel as shown in figure 1, awareness > consideration > intent > purchase.

Figure 1 – Purchase Funnel

Figure 2, illustrates the different keyword searches a person might make whilst refining a t-shirt purchase decision. Searches can be identified in blue. The person starts by searching for “T-Shirts” for research, but ends with a high-level intent search that includes the company brand name “” the colour “Red” and the size “XL”.

Figure 2 – Purchase Funnel Stages & Keywords

Last Click Model
The last-click model is still very popular today and this largely stems from it historically being the default attribution model of Google Analytics and Google Adwords. In addition, it also rewards short payback periods, enabling you to capture high intent traffic. This is because with the last-click model all credit is passed to the final click. Once you have exhausted the high intent, bottom of the funnel traffic, it will be harder for you to justify spend on research / awareness traffic at the top of the funnel with last-click attribution.

Using figure 2 and the last-click model, 100% of the credit would be given to the last-click search “ Red XL”. All the other searches would have no credit attributed to their campaign.

Figure 3 – Last Click Model

First Click Model
With the first-click model (see figure 2) all credit is passed to the first click. This model is useful to assess the value of awareness campaigns at the top of the funnel. It is used by businesses where initial awareness is the key success factor in completing purchases (customers less likely to shop around).

Using figure 2 and the first-click model, 100% of the credit would be given to the first-click search “T-Shirts”. All the other searches would have no credit attributed to their campaign.

Figure 4 – First Click Model

Linear (even distribution) Model
With the linear model credit is distributed evenly. Each visit to the site considered as important as the other.

Using figure 2 and the linear-click model, all 3 searches would equally receive 33.3333% of the credit.

Figure 5 – Linear Model

Time Decay Model
With a time decay model (see figure 6), credit is allocated to clicks based upon the time between click and purchase. In this example the longer the time between the click and the purchase the lower the credit assigned to that click. This suits a business with an impulse nature, where the more time a customer takes the less likely they are to purchase.

Using figure 2 and the time decay model and assuming, 1-day past in between each search, then “T-Shirts” would get 14.29%, “Red T-Shirts” 28.58% and “ Red XL” 57.16% (approximately).

Figure 6 – Time Decay Model

U-Shaped or Position-Based Model
U-shaped or Position-Based Models (see figure 7) have become popular in the last few years due to a belief they allocate credit fairly across the purchase funnel. With this attribution model, 40% of the credit is allocated to the first and last clicks. The remaining 20% is allocated to the clicks in between. If the path length is just 1 or 2 click then the credit is shared accordingly. Favoured by businesses where there is still new customer growth in the market and so awareness is a key factor, but also where competition is high and specific product searches return many results.

Using figure 2 and the U-shaped model, 40% of the credit would go to “T-Shirts” and “ Red XL” first and last searches. 20% of the credit would go to the middle search, “Red T-Shirt”.

Figure 7 – U-Shaped or Position-Based Model

Conversion Windows
A conversion window is the period of time after a customer clicks an ad during which a conversion, is made and recorded. The longer the period, the more conversions that will be attributed to your advertising campaign. If you set 7-days, then a conversion that takes place 8-days after clicking your ad won’t be attributed to you campaign. Google Adwords uses a post-click 30-day cookie and now offers an additional 1-day post-view option.

Post View
Google and Facebook Advertising programmes now include post-view attribution, set to 1-day. What is means is that is someone sees your ad but does not click and makes a purchase online within 1-day of the impression, then that sale will be attributed to your campaign.

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