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This is the End of Conversion Rate Optimisation

…at least as you know it.

Conversion rate optimisation (CRO) is a system for increasing the percentage of visitors to a website that convert into customers, or more generally, take any desired action on a webpage.” This is how Wikipedia defines the pretty popular online-marketing technique that seems to solve all of our performance problems. But does it really?  

It is with full intention, that we close our e-commerce-series of blog-posts with a rather inflammatory topic. In E-com it is said, the most important KPI is conversion rate and increasing it is always one of the top priorities. Therefore we can’t not address this key topic in the blog-series and hence want to give some ideas for thought from our perspective as testing experts.

What even is conversion rate?

Conversion rate is the ratio between the number of conversions (e.g. completion of a purchase) and the number of total visitors on the website. For example, if your online-shop had 15 sales and 480 visitors last week, your conversion rate is 15 divided by 480 (0.031), multiplied by 100 = 3.1%. The calculative formulation of this KPI makes it a quantifiable indicator – a hard fact – that is easy to compare and measure and thus gives a perfect base for optimisation efforts. This is good, isn’t it?

How does the conversion rate get optimised – the classical Multivariate (A/B) testing approach?

The classical approach of conversion rate optimisation for webshops often is a multivariate concept, where marketers follow the pattern of small, iterative steps with one or multiple test variations of the same item, e.g. A/B-Testing of different designs, buttons, grids, etc. of a page.
This is often done by following these steps:

1. Research phase:
Marketers identify the areas that can be improved

2. Hypothesis Phase:
A hypothesis is defined. For example the orange CTA-button leads to more clicks than the dark-blue button

3. Testing Phase:
Both versions go live for a period of time, the visitors of the page are split 50/50 each group seeing one of the buttons coloured as described above

4. Learning Phase:
Test results get analysed, the winner gets implemented

Sounds like a pretty valid process, it’s measurable, there is a quantitative KPI-Goal, boom, conversion rate increases with every iteration, right?

The Downside of the classical CRO approach

Well, it all sounds like a good plan, but (and I am sorry to disturb the peace) now comes the drawback. There are some significant disadvantages of this method, as it completely lacks a qualitative dimension. A dimension that is key in every business, namely, the customer.
Other major downsides of the classical process include:

  • Operational blindness in test setup
    As you mostly build your A/B versions internally they are biased. An ongoing internal testing process makes this prepossession incrementally worse with every iteration, because for the next optimisation journey you only take biased learnings into account.
  • Time and volume of visitors
    The standard approach is quantitative – this benefit is also a drawback. If your shop or your specific micro-conversion you are aiming to optimise is too small, your test will run forever and never ever will get significant results.
  • Loss of time and speed for your team due to limited resources and ability to scale
    Always an issue – if you want to do everything internally you will have to invest a lot of time to build something solid in every iteration. Especially if you want to continuously integrate a testing approach in your organisation.
  • Conversion Rate Increases are mostly  marginal
    The more you test, the smaller your conversion rate increases will be. As you get closer to the “best-possible” experience your increases will shrink from iteration to iteration.
  • Quality Assurance is often only rudimentary due to limited resources
    This, like most parts of digital development, is one of the most underestimated areas of CRO. Did you test your last Challenger Versions in every browser on any device? If not you might have screwed your results already.

Customer-Centric Conversion Optimisation

Customer Centricity is key if you really want to make an impact on your conversion rate. The classical A/B Testing might get you somewhere, yes, but test scenarios are always just made up of hypothesises – i.e. on the basis of limited evidence as a starting point – not by real proof.
Often Marketers rely on best practices like “strong colours for CTA drive clicks” and “time-limited offers drive sales”, which may be the right way for many online-shops, but is it the best approach to get YOUR conversion rate to the next level? You won’t know, until you focus on your individual case, meaning on your customers and what is relevant to them.

That’s why we recommend starting with the customer. Focus on your specific target group early when setting up test scenarios to evaluate what really is relevant for them to convert. FYI: this might not be the colour choice of a CTA-Button. Before performing the live test, make sure everything works and is bug-free. Often the B-Version of an A/B-Testing gets tested merely superficial and bugs in this version distort the whole test result.

360° Approach for Conversion Rate Optimisation


At Testbirds we formulated the Testbirds 360° approach for Conversion rate optimization, which includes the following steps:

1. Research phase and set up of testing Hypothesis with the help of your customer:
Start your conversion rate program for example with a BugAbility™ test on your online-shop. This way you can make sure that the current site is bug-free. You are also able to get user feedback from your custom audience regarding Usability & UX with which the following variations in the test are already reviewed by your custom audience.

2. Pre-testing the different variations before live-Testing:
Let the crowd check your test-versions before the actu

al test in order to make sure you get error-prone and unadulterated results, that are not manipulated by functional errors. A perfect way to do so is, for example, by executing a Prototype Evaluation through a Usability & UX Study, or a classic Exploratory Bug Test.

3. Testing Phase and Learnings:
In the actual live-testing phase, you are ensuring a flawless and error-resistant set up, which makes the results much more reliable and relevant. The benefits of a customer-centric CRO-plan speak for themselves:

  • Customer Centricity
    Faster and more target-group-specific feedback from your particular audience
  • Save on resources
    Use our crowd and dedicate your employees to other projects and tasks
  • Higher efficiency with every iteration cycle
    Boost  conversion rates faster than ever before
  • Works for small and big traffic websites, shops, apps

Conversion Rate Optimisation – we are happy to help

If we got your attention with this topic, here’s an idea: let’s talk about it in more detail and if you’re ready with regards to your specific business or case. In a few weeks, DMEXCO, the largest congress trade fair for the digital industry in Europe, is taking place in Cologne. We are going to be there and already are looking forward to this event. Why not make an appointment with us right now and come to our booth on 11th or 12th of September?
Between us I can reveal that we are planning of bringing some testers with us, so that you can get direct feedback on specific pain points on your online store immediately at our booth. AND don’t forget, you can also win some DMEXCO Tickets or free Device Cloud Packages, when you sign up for a meeting.

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About the author

Markus is responsible for the online appearances of the Testbirds. Should he be offline, he has been trying for years in the high art of golf – unfortunately in vain.



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Testbirds specialises in the testing of software such as apps, websites and Internet of Things applications by using innovative technologies and solutions. Under the slogan, “Testing Reality”, the company offers various testing methods to its clients looking to optimise the user-friendliness and functionality of their digital products. With over 250,000 registered testers located in 193 countries, Testbirds is one of the world’s leading crowdtesting providers. In addition, the IT service provider utilises cloud based technologies to support customers in the optimisation of their digital products. The combination of the two testing methods delivers a unique and extensive portfolio that


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