Many eBusiness managers ask how they can argue for usability investments and how they can measure the return-on-invest (ROI) of usability methods. There is not much serious literature available on this topic and the web is spammed with voodoo economics and rather doubtful metrics of usability ROI.

Usability experts, however, should have some comprehensible answers if clients approach them with the ROI question.

First of all, usability has a ROI. This is a widely accepted truth. The problem is, measuring the ROI is not so easy, especially because in most cases comparative data is not available and typically usability is not the only action taken to increase the quality of an eCommerce website.

Luckily, in eBusiness the ROI of usability can sometimes be measured more easily. If the business runs professional traffic analysis tools, there are some metrics that make usability ROI traceable. For example, if changes to the design of your checkout process result in an increased conversion rate, this can be the benefit of usability engineering. Most likely, such benefits can be measured well because they are the result of a pipelined process, such as the checkout at an online store. If you also changed the presentation of your shopping basket such that cross references to other attractive products appear before the customer proceeds to the checkout, you might even be able to increase the average value of the shopping basket.

While this might sound good on the first sight, the above example does imply a critical problem. If you try to measure the usability ROI after you have implemented both changes, will you be able to determine which usability method has increased the commercial success of your site? And guess you also changed the information architecture and search process in order to make people find your products more easily. Will you still be able to tell your CEO which part of the usability effort really impacted the sales figures?

I’d say no, you are not.

The nightmare of metrics gets even worse, if the marketing department runs an online campaign at the same time. Or, the other way around, cancels a larger amount of marketing activities. If the conversion rate then suddenly decreases to a level even lower than before usability methods were applied, how can you still argue that your usability spending has a ROI?

Measuring the ROI of usability would therefore demand to take one step after another in redesigning your website for more usability. As this would critically defer the time to market, there is not really a straightforward approach to measure the ROI of usability on the basis of figures from traffic analysis data in most project settings.

Even though you might be able to deduce some arguments from analysis data, the facts you will be able to present might be annulled by others easily.

In order to understand the ROI of usability engineering, you have to consider several aspects.

First of all, you have to understand that increasing a site's usability must not be restricted to specific processes, such as the checkout. The challenge rather is to make visitors find and use the processes and applications you provide. If people are unable to find a product or a service, even the most usable checkout design won't help. Again, you will most likely identify increased site usability by the sales figures of your store. But you must understand that the improvement does not just come from a newly designed checkout. If people do not find the products they are looking for, they will not even access a checkout or inquiry process. They will rather remember your store as a dealer with unfriendly sales staff and a bad allocation of products.

Second, and as a consequence of the above mentioned, you have to consider that usability already starts on the home page (or even at the search engine that leads to the right landing page) and continues to play a major role during several other processes, especially the search and find process. The ease of finding products is linked to the filtering and focusing information on your site. The architecture of your site should provide a clear guidance and support different access strategies, e.g. browsing vs. searching for products.

Third, a strictly process-driven design of your website is not a very good strategy. Most users will not access the content of your site in the way you expect. As a website manager, you should think about the motivation why people come to your website and take different types of visitors into account. Once you have an imagination about people's goals and what people expect from your site, you will be able to design an UI architecture that enables a high user experience by providing many ways of interacting with your site.

Altogether, arguing for usability investments should not exclude specific parts of your digital sales channel. If you invest in ease of use with a broader perspective, you can increase the user and customer experience by enabling people to find, understand and buy your products with less effort and in less time. Moreover, ease of access to your product landscape might allow decreasing your headcount of customer support and call-centre agents. A certain amount of usability ROI therefore also comes from decreased total costs of ownership.

Continuous usability testing or customer surveys are the better choice compared to traffic analysis. Monitoring real users while they interact with your site or querying your customers after they ordered a product will give you a much better impression about user (dis-)satisfaction. Unlike vague interpretations from marketing and product management, usability testing will show you how your users and customer really think. Moreover, the effort to invite real end-users to usability testing sessions is usually much lower that the implementation and maintenance of a non-standard traffic analysis tool - which coincidentally is usability ROI again.