Article

5min read

Mutually Exclusive Experiments: Preventing the Interaction Effect

What is the interaction effect?

If you’re running multiple experiments at the same time, you may find their interpretation to be more difficult because you’re not sure which variation caused the observed effect. Worse still, you may fear that the combination of multiple variations could lead to a bad user experience.

It’s easy to imagine a negative cumulative effect of two visual variations. For example, if one variation changes the background color, and another modifies the font color, it may lead to illegibility. While this result seems quite obvious, there may be other negative combinations that are harder to spot.

Imagine launching an experiment that offers a price reduction for loyal customers, whilst in parallel running another that aims to test a promotion on a given product. This may seem like a non-issue until you realize that there’s a general rule applied to all visitors, which prohibits cumulative price reductions – leading to a glitch in the purchase process. When the visitor expects two promotional offers but only receives one, they may feel frustrated, which could negatively impact their behavior.

What is the level of risk?

With the previous examples in mind, you may think that such issues could be easily avoided. But it’s not that simple. Building several experiments on the same page becomes trickier when you consider code interaction, as well as interactions across different pages. So, if you’re interested in running 10 experiments simultaneously, you may need to plan ahead.

A simple solution would be to run these tests one after the other. However, this strategy is very time consuming, as your typical experiment requires two weeks to be performed properly in order to sample each day of the week twice.

It’s not uncommon for a large company to have 10 experiments in the pipeline and running them sequentially will take at least 20 weeks. A better solution would be to handle the traffic allocated to each test in a way that renders the experiments mutually exclusive.

This may sound similar to a multivariate test (MVT), except the goal of an MVT is almost the opposite: to find the best interaction between unitary variations.

Let’s say you want to explore the effect of two variation ideas: text and background color. The MVT will compose all combinations of the two and expose them simultaneously to isolated chunks of the traffic. The isolation part sounds promising, but the “all combinations” is exactly what we’re trying to avoid. Typically, the combination of the same background color and text will occur. So an MVT is not the solution here.

Instead, we need a specific feature: A Mutually Exclusive Experiment.

What is a Mutually Exclusive Experiment (M2E)?

AB Tasty’s Mutually Exclusive Experiment (M2E) feature enacts an allocation rule that blocks visitors from entering selected experiments depending on the previous experiments already displayed. The goal is to ensure that no interaction effect can occur when a risk is identified.

How and when should we use Mutually Exclusive Experiments?

We don’t recommend setting up all experiments to be mutually exclusive because it reduces the number of visitors for each experiment. This means it will take longer to achieve significant results and the detection power may be less effective.

The best process is to identify the different kinds of interactions you may have and compile them in a list. If we continue with the cumulative promotion example from earlier, we could create two M2E lists: one for user interface experiments and another for customer loyalty programs. This strategy will avoid negative interactions between experiments that are likely to overlap, but doesn’t waste traffic on hypothetical interactions that don’t actually exist between the two lists.

What about data quality?

With the help of an M2E, we have prevented any functional issues that may arise due to interactions, but you might still have concerns that the data could be compromised by subtle interactions between tests.

Would an upstream winning experiment induce false discovery on downstream experiments? Alternatively, would a bad upstream experiment make you miss an otherwise downstream winning experiment? Here are some points to keep in mind:

  • Remember that roughly eight tests out of 10 are neutral (show no effect), so most of the time you can’t expect an interaction effect – if no effect exists in the first place.
  • In the case where an upstream test has an effect, the affected visitors will still be randomly assigned to the downstream variations. This evens out the effect, allowing the downstream experiment to correctly measure its potential lift. It’s interesting to note that the average conversion rate following an impactful upstream test will be different, but this does not prevent the downstream experiment from correctly measuring its own impact.
  • Remember that the statistical test is here to take into account any drift of the random split process. The drift we’re referring to here is the fact that more impacted visitors of the upstream test could end up in a given variation creating the illusion of an effect on the downstream test. So the gain probability estimation and the confidence interval around the measured effect is informing you that there is some randomness in the process. In fact, the upstream test is just one example among a long list of possible interfering events – such as visitors using different computers, different connection quality, etc.

All of these theoretical explanations are supported by an empirical study from the Microsoft Experiment Platform team. This study reviewed hundreds of tests on millions of visitors and saw no significant difference between effects measured on visitors that saw just one test and visitors that saw an additional upstream test.

Conclusion

While experiment interaction is possible in a specific context, there are preventative measures that you may take to avoid functional loss. The most efficient solution is the Mutually Exclusive Experiment, allowing you to eliminate the functional risks of simultaneous experiments, make the most of your traffic and expedite your experimentation process.

References:

https://www.microsoft.com/en-us/research/group/experimentation-platform-exp/articles/a-b-interactions-a-call-to-relax/

 

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Article

5min read

Tapping into Emotional Marketing | Talia Wolf

Talia Wolf reveals how emotional marketing can revolutionize your experimentation process and lift conversions.

Taking a customer-centric approach to marketing, founder and CEO of Getuplift, Talia Wolf, harnesses the power of emotional marketing techniques to increase visitor conversions. 

Her natural interest in conversion rate optimization (CRO) and experimentation was sparked through her early work in a social media agency, later moving on to become an expert in the field – consulting for many companies on the subject, and speaking on stage at Google, MozCon and Search Love.

Guest host and AB Tasty’s Head of Growth Marketing UK, John Hughes, spoke with Talia about emotional marketing as a tool for optimization, delving into how customer research can facilitate the experimentation process, reduce the rate of failure, and earn the buy-in from company stakeholders.

Here are some of the key takeaways from their conversation.

Based upon the idea that emotion drives every single decision that we make in life, the emotional targeting methodology shifts the focus of your online marketing content from your solution, features, or pricing, to your customer. Rather than playing a guessing game and simply reshuffling elements on a page, this technique requires a deeper understanding of human behavior. By identifying customer intent and buying motivation, you can create an optimized experience, which meets their needs and increases conversions.

Backed by academic research, the fundamental role of emotion in our daily choices can be integrated into your strategy to better cater to your customers by figuring out a) their biggest challenges and, b) how they want to feel after finding a solution. What is their desired outcome? 

With this in mind, you can optimize your digital communications with high-converting copy and visuals that speak directly to your customers’ needs. By shifting the conversation from the product to the customer, an incredible opportunity opens up to scale and multiply conversions.

Firstly, experimentation should be backed by research. From customer and visitor surveys, to review mining, social listening and emotional competitor analysis, Talia encourages extensive research in order to create the most likely hypothesis upon which to base an A/B test. 

Once you know more about your customers, you can review the copy and visuals on your product page for example, and from your research you might discover that your content is not relevant to your target customer. You can then come up with a hypothesis based on their actual needs and interests supported by compelling social proof, and write a brief for your designer or copywriter based on the new information. 

From there you can build your experiment into your A/B testing platform with a selected North star metric, whether it’s check-outs, sign-ups or add-to-carts, to prove or disprove your hypothesis. And, while we know that nine out of 10 A/B tests fail, emotional marketing facilitates the hypothesizing process, strengthening the chance of creating a winning experiment by testing variables that can actually impact the customer journey.

How to persuade stakeholders to support your experiments.

When it comes to CRO, there are often too many chefs in the kitchen, especially in smaller organizations where founders have a concrete vision of their customers and their messaging. 

Talia explains that a research-based approach to experimentation can offer reassurance as part of a slow-and-steady strategy, backed by evidence. This personalized methodology involves talking to your customers and website visitors and scouring the web for conversations about your specific industry, rather than simply following your competitor’s lead.

It becomes a lot easier to propose a test to a founder or CEO when your hypothesis is supported by data and research, however, Talia recommends resisting the urge to change everything at once and rather, start small. Test the emotional marketing in your ads or send out an email sequence requiring only a copywriter, and share the results.

When you’re trying to get buy-in, you need to have a strong hypothesis paired with good research to prove that it makes sense. If this is the case, you can demonstrate the power of emotional marketing by running a couple of A/B tests: one where the control is the current solution-focused content and the variant is a customer-focused alternative, and another which highlights how customers feel right now versus how they want to feel – two important variations which help you to relate better to your customer. The key to garnering support is to take baby steps and continuously share your research and results.

What else can you learn from our conversation with Talia Wolf?

  • Why B2B purchases are more emotional than B2C. (15:50)
  • How to stand out in a crowded market by knowing your customer. (20:00)
  • How emotional marketing impacts the entire customer journey. (25:50)
  • How to relate to your customer and improve conversions. (32:40)

About Talia Wolf

Conversion optimization specialist Talia Wolf is the founder and CEO of Getuplift – a company that leverages optimization strategies such as emotional targeting, persuasive design, and behavioral data to help businesses generate more revenue, leads, engagement and sales. 

Starting her career in a social media agency, where she was introduced to the concept of CRO, Talia went on to become the Marketing Director at monday.com, before launching her first conversion optimization agency, Conversioner, in 2013. 

Today, with her proven strategy in hand, Talia teaches companies all over the world to optimize their online presence using emotional techniques.

About 1,000 Experiments Club

The 1,000 Experiments Club is an AB Tasty-produced podcast hosted by Marylin Montoya, VP of Marketing at AB Tasty. Join Marylin and the Marketing team as they sit down with the most knowledgeable experts in the world of experimentation to uncover their insights on what it takes to build and run successful experimentation programs.