Guide: Defining Traffic Allocation

Complete guide on how to define traffic allocation depending on the different campaign types, including specifications on how to use the dynamic allocation.

Generalities

Traffic allocation is the fifth step of the campaign creation flow. When creating a test or a personalization campaign, you need to define the percentage of visitors allocated to the variation(s) (in case of a test) or scenario(s) (in case of a personalization) and the original version of your website.

By default, the traffic is equally shared between the original and the variations (50/50 if there is just one variation plus the original, 33/33/33 if there are two variations, etc.), but this is fully configurable in the test options. You can set the percentage of your traffic that will be allocated to each version.

This table shows the different categories of users representing your entire website traffic. For each category, information on what the users will see is displayed:

How to Set Up Traffic Allocation by Type of Campaign

A/B Test

Set up the traffic allocation on the A/B test from step 5 Traffic allocation of the creation flow. 

By default,100% of your visitors will go through the campaign and the traffic will be split equally between the original and the number of variations of your test. In our example with one variation, 50% of the traffic will be allocated to the original and the other 50% to the variation.

You can always change this configuration and also split the traffic between each variation.

Multipage Test

Set up the traffic allocation on a multipage test from step 5 Traffic Allocation of the creation flow. 

By default, 100% of your visitors will go through the campaign, the traffic will be split equally between the original and the number of variations of your test. 

In our example with one variation, for each page: 50% of the traffic will be allocated to the original and the other 50% to the variation. 

You can always change this configuration and also split the traffic between each variation. 

Multivariate Test

Set up the traffic allocation on a multivariate test from step 5 Traffic Allocation of the creation flow. 

Each percentage of the targeted traffic is allocated to a subtest. Do not forget to set up traffic allocation for each subtest of your campaign using the dropdown.

All users must be tracked on a multivariate test.

Patch Campaign

The Traffic allocation step is not available for Patch campaigns, meaning that 100% of your traffic will see your patch.

Simple Personalization

Set up the traffic allocation on a Simple personalization from step 5 Traffic Allocation of the creation flow. 

By default, 100% of your global traffic is allocated to your experience. Although, we recommend leaving at least 10% of your traffic on the original version (depending on the amount of traffic on your website) to be able to control the performance of your experience, make a comparison with the original and measure the ROI of the campaign on the ROI dashboard.

Multipage Personalization

Set up the traffic allocation on a Multipage personalization from step 5 Traffic Allocation of the creation flow. 

Each percentage of the targeted traffic is assigned to a page. Do not forget to set up traffic allocation for each page of your campaign using the dropdown. 

By default,100% of your global traffic is allocated to your experience but you can change this configuration.  

Multiexperience Personalization

Set up the traffic allocation on a Multiexperience personalization from step 5 Traffic Allocation of the creation flow. 

Each percentage of the targeted traffic is allocated to an experience. Do not forget to set up traffic allocation for each experience of your campaign using the dropdown. 

By default,100% of your global traffic is allocated to your experience but you can change this configuration. 

Dynamic Allocation Option

Dynamic traffic allocation is based on a statistical research topic called “multi-armed bandit”. The goal of this algorithm is to limit the loss due to the lowest-performing variations. 

However, when the campaign has just been launched, the performance of the variations is not known yet. When data collection begins, the performance of variations is known progressively, but these measures are not fully significant.

At this point, it would be an error to send all traffic to the apparent winner. However, some formulas can help to compute the right amount of traffic to send to each variation with the following goal: sending more traffic to the variation that could win, but not too much, otherwise, there would not be enough traffic to ensure the measurement of the supposed losers.

The solution is to periodically change the allocation regarding previous data, following a statistical formula that ensures the goal mentioned above.

Configuration

Before switching to dynamic allocation, you need to define at least a primary goal in the Goal step of the test creation flow. The Dynamic allocation algorithm is exclusively based on this primary goal. This means that it detects the best-performing variation based on the increase in conversions of the primary goal. For further information, please refer to the Metrics guide & definitions.

Heads up ⚡️

👉 The primary goal can be any type of goal except Browsing metrics (Revisit rate, Pages per session, and Bounce rate).

👉 To activate dynamic allocation, click the Change/switch to Dynamic allocation button at the top of the page. 

A confirmation message is displayed. By confirming, the traffic allocated to each variation will be determined based on the predictive algorithm and on the primary goal, you configured for your test. At this point, you will not be able to manually adjust the percentage of traffic allocated to each variation. However, you are still able to define the percentage of traffic you want to allocate to your test and the percentage of traffic you want to leave untracked.

Heads up ⚡️

If you did not select a primary goal, you will not be able to switch/change to dynamic allocation. In this case, you will be asked to define at least one primary goal and you will be redirected toward the goal step. 

Once the test has been launched, you can access the reporting anytime, as you would for any campaign with static allocation.

From the test dashboard, tests using dynamic allocation are easily identifiable thanks to the   icon.

Once your test has been launched with dynamic allocation, you will not be able to perform the following actions:

👉 Change the primary goal

👉 Add, remove or duplicate a variation within the test

👉 Switch back to static allocation

If you want to perform any of these actions, you need to pause the test and duplicate it.

Use Cases

Dynamic Allocation can be very useful in the following cases: 

👉 When you want to optimize micro conversions that are expected to occur within a short period after the user has been exposed to a variation. For instance, e-commerce, prefers the Add to cart goal rather than the transaction, as the primary goal.

👉 When you have very little time to run a test (ex: testing the headline of a media article, testing the message of a countdown banner).

👉 When you have really low traffic on the page you want to test, but still want to do some optimizations. Dynamic allocation carries out optimization even before reaching enough data to be fully significant. This would not be very interesting because the traffic is low.
But it may become interesting if carried out on a high number of pages. For instance, if you have low traffic on each product page, you cannot carry out a classic A/B test. But it may be interesting to implement multiple dynamic allocation tests, one for each product page. The gain will be low for each page, but it can be more significant when multiplied by the number of pages.

👉 When you have a lot of variations to test (more than six), dynamic allocation enables you to quickly identify the lowest-performing variations to run the test on the most relevant ones.

Heads up ⚡️

We recommend not using dynamic allocation in case you want to optimize a meal-ordering website.
Since allocation changes over time, the primary goal should be stable during the experiment.

Tips on How to Use Traffic Allocation

Traffic Percentage Between Variations

We recommend splitting equally the traffic between the original and variation(s) for statistical reliability.

But you can allocate more traffic to your variation(s). Drag the Traffic allocated to the variation slider towards the right or add more than 50% of traffic into it.

You can set the percentage of your traffic that will be allocated to each version.

Untracked Traffic

For example, let’s say you have implemented a ‘risky’ test and want to limit risk-taking. In this case, you can limit the number of visitors tracked so that 40% of visitors are not tracked. This way, you reduce the test sample and limit the visibility of your new version(s). This means that 40% of untracked visitors will see the original version of your website but will not receive a cookie in their browser related to the test. Their actions on the website will not be tracked unless you decide to increase the percentage of tracked visitors.

The percentage of visitors you track depends on the volumetry of your website. For example, if your website has over 10M unique visitors per month, you can choose to track only 20% of the entire traffic (and limit the test sample to 20%). However, if you have around 200k unique visitors per month and decide to track 20% of the traffic, you will not reach reliability quickly enough to determine whether or not you can increase the percentage of tracked visitors. 

For more information about the calculation of the traffic, you would test regarding your needs, refer to our Sample Size Calculator article in the AB Tasty blog.

To get more information about reliability and the chance to win in the reports, please visit our specific guide Campaign reports.

Traffic Allocation Changes

We recommend keeping the same traffic allocation throughout the campaign duration.

Heads up ⚡

If you change the traffic allocation while your campaign is live, only the new visitors will be affected by this change. 

Visitors who have already been affected by a variation (before this change) will keep on seeing the same variation.

If you want to change the traffic allocation of the test to assign 100% to the variation, you think is the highest-performing after analyzing your report, you need to create a patch campaign from the current test. Otherwise, people who have a cookie from another variation or the original version will continue to see the original version of your website. 

Comparison in Personalization Campaigns

If you allocate 100% of your traffic to your experience, you will not be able to make a comparison with the original version. We recommend leaving at least 10% of your traffic on the original version (depending on the amount of traffic on your website) to be able to control the performance of your experience, make a comparison with the original and measure the ROI of the campaign on the ROI dashboard.