Google Analytics is a powerful tool that every paid search manager should be using to measure the impact of their campaigns. Lately, I’ve been asked about the various attribution models in Google Analytics. In this blog post, we will be reviewing the default attribution models, breaking down the differences between each, and finally answering the question, “What is the best attribution model?” As defined by Google, “An attribution model is a rule, or set of rules, that determines how credit for sales and conversions is assigned to touch points in conversion paths.”

Google Analytics Attribution Model Guide

Google offers seven default attribution models to slice and dice your data as you see fit. It also provides a plethora of custom options for advanced users. The models are as follows: Last Interaction, Last Non-Direct Click, Last AdWords Click, First Interaction, Linear, Time Decay and Position Based. Attribution models can be found by navigating to the conversion drop down on the left menu bar in Analytics. From there, click on the attribution drop down and then the model comparison tool. Next, I will breakdown the definition of each attribution model and give an example of how it would be used. Along with each example I will highlight the impact on real paid search data that we have collected over the last six months. We will also be using an actual customer journey pulled from Google Analytics to better understand each attribution model.

The Customer Journey

To illustrate the importance of the different attribution models, we will be using the customer journey you see below. This is the real path of a searcher as captured by Google Analytics. This customer first visited the website after clicking on a paid search ad, then visited directly three times, visited from a referral link, clicked on another paid search ad, visited directly again, one more referral and finally visited directly four times before converting.

Some conversion paths are only one step, resulting from users who convert immediately after visiting a website for the first time. The length of your conversion path is often dependent on your industry and your product. For companies that have longer sales cycles, it is not uncommon for conversion paths to average 10+ touch points.

Last Interaction Attribution Model

Last interaction is just as it sounds. It is the last interaction or the last touch point in the customer journey before a conversion was recorded. The last interaction will receive 100% of the credit for the conversion. Last interaction is a useful attribution model because it gives you insight into which channel was the last step in the journey before a conversion took place.

In this case, the last direct visit would receive credit for the conversion. In the example above, you can see that when filtering by last interaction, the paid search channel has a 286% return on ad spend. We also received 31 conversions in the six month time span that had a conversion value of $14,760.75. Last interaction is an excellent model to use when trying to figure out which channel results in the most conversions while not taking into consideration the previous visits.

Last Non-Direct Click Attribution Model

The last non-direct click attribution model ignores all direct visits when taking the conversion path into consideration. Last non-direct click is the default attribution model in Google Analytics. In the customer journey example above, the referral traffic would receive 100% of the credit for the conversion. Last non-direct click is useful for determining the impact of specific channels while taking direct visits out of the equation.

Here, the ROAS from the paid search campaign jumped from 286%, using the last interaction model, up to 398% using the last non-direct click attribution model. Conversions increased, cost per acquisition decreased and conversion value increased. Many users will visit a site multiple times before converting through a direct visit. Last non-direct click helps paint a better picture of the effectiveness of your marketing efforts and is one of the most widely used models.

Last AdWords Click Attribution Model

A personal favorite of mine, the last AdWords click attribution model gives 100% of the conversion credit to the last AdWords ad that was clicked, regardless of where it landed in the overall customer journey. In the example above, the second AdWords ad would get credit for the conversion. Last AdWords click is arguably the best model to review when trying to quantify the effectiveness of a paid search campaign.

If an advertiser limits themselves to looking at data through the lens of the default Google Analytics attribution model, they may miss out on important insights, and ultimately pause a profitable campaign. Since many users do not convert directly on their first visit, understanding the impact an ad had early on in the customer journey is essential. From the screenshot above you can see that viewing the last AdWords click attribution model provides a 604% ROAS.

First Interaction Attribution Model

The exact opposite of last interaction, “first interaction” gives 100% of the conversion credit to the channel the customer interacted with first. Below, you can see that the first paid ad would receive credit for the conversion. First interaction is important since it identifies the marketing channel that helped you acquire that customer.

First interaction attribution model is perfect for analyzing the effectiveness of new user acquisition campaigns. In the customer journey example, the first touch point came from a non-brand keyword. Although they did not convert on the first visit, you can see the importance of running a non-brand keyword campaign, since the user eventually came back through multiple visits and converted. Without the initial visit from a paid ad, they may have never found the business.

Linear Attribution Model

Linear attribution model is one of the least used attribution models among paid search managers. With linear attribution, each touch point in the conversion path is assigned an equal share of credit for the conversion. Using the customer journey above, each channel would receive a portion of credit for the conversion.

Linear attribution makes sense for your business if you want to give each touch point a slice of the pie. Although, as I mentioned above, most advertisers shy away from using it. From the data above, you can see the paid search channel has a 292% ROAS using the linear attribution model.

Time Decay Attribution Model

The time decay attribution model is the second to last model we will be reviewing today. With time decay, more credit is assigned to the channels closest to the final conversion. In our example above, the majority of credit would be assigned to the direct visits. The referral channel would receive less credit and the first paid search ad would receive the least amount of credit.

If you tend to put more weight in touch points closer to the final conversion, then time decay is for you. New customer acquisition campaigns will typically struggle to show a significant return on ad spend. This is due to putting less weight on the earlier touch points in the journey. You will often see direct traffic leading the way for time decay or any later touch attribution models.

Position Based Attribution Model

The position based attribution model divides credit up into three areas. 40% of the credit is given to the first interaction. 40% of the credit is given to the last interaction. The remaining 20% is evenly distributed into the channels between. In the example above, 40% would be given to the direct visit and 40% would be given to paid search. The other channels would receive 4% each.

In my opinion, position based attribution showcases the most complete story of the customer journey. By giving the most credit to the first and last touch you get the best idea of how a customer found you and when they converted. As well as giving a bit of credit to any channels that appeared in the middle of the conversion funnel. Most advertisers who understand the benefits of position based attribution and the overall customer journey will create a custom position based attribution model to fit the needs of their business.

Which attribution model is best?

The short answer: it depends. It truly depends on your business goals and what you want to track. Are you trying to understand the channel that ends with the most conversions? You’ll want to review the last interaction attribution model. Do you want to quantify the impact of paid search? Last AdWords click will make you look like an SEM rock star. Need to show the results of your non-brand new customer acquisition campaign? First interaction is the way to go! In most cases, it’s best practice to consider a few attribution models when making adjustments. You will be able to identify the strengths of each marketing channel independently based on the goals you have set. As always, if you have any questions, feel free to drop us a line, we are always happy to discuss the best attribution model for your website!

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