May 23 2007

Put Your Web Site to the Test

Effective testing is the key to Web site improvement.


“I don’t know who discovered water, but I’m pretty sure it wasn’t a fish.” Coined by the media guru and professor Marshall McLuhan, the aquatic metaphor sums up how we lose objectivity once we’re immersed. When building a Web site, or graphical-user interface, objectivity becomes problematic. As this familiarity grows, it becomes increasingly hard to discern how our perceptions vary from those of the customer. This perception gap can create customer-experience blind spots the size of the Bermuda Triangle.


Web site testing is the best way to evaluate longstanding assumptions and get a better understanding of what your site visitors desire. Two methods of testing can help site owners learn from their customers: A/B testing and facilitated usability testing. A/B testing works best when you have a well-defined goal and need to choose between a few clear alternatives. Facilitated usability testing is the better choice for more complex design challenges requiring a deeper understanding of user behavior.

While there are numerous variations, traditional usability testing usually involves a facilitator providing actual customers with some tasks to achieve on the Web site. Participants are recruited from the actual customer base or from a carefully screened set of participants who match the target profile. Web site managers and the development and design team will often watch in real time, either behind one-way glass or via a Web cast. The facilitator will carefully ask questions before, during and after the tasks to understand the participants’ actions.

A/B testing involves comparing one version against another based on a desired outcome. For example, two registration pages might be created with different instructional text on each. Presumably the one that is successfully completed more often is better. Commonly tested elements include graphics, blocks of text, titles and form fields. A/B testing is a game of numbers, requiring a substantial sample size. It uses Web metrics to track performance data and draws comparisons between versions.

Choosing the Best Method

A common question is “which method is better?” The more appropriate question, however, is “which do I use when?” The information and decisions required should drive the selection of testing methods. For complex design challenges that require a richer understanding of customer motivation, a good usability facilitator can help ask the questions that unravel the hidden meaning behind user actions. Such insight can be hard to find in the reams of statistics provided by A/B testing.

This was the case for Blue Coat, a Sunnyvale, Calif.-based manufacturer of network products. Its challenge went beyond the browser to include the physical product, the user environment and more. In one study, team members took beta products to customer sites, observing and asking questions as they unpacked the product, reviewed (or ignored) the documentation, set up the security appliance online, and then configured it using their Web browser. Some of the findings during this process could never have been replicated through A/B testing of two versions of an interface component.

“Our best insight comes from watching and listening carefully to our customers. Through such interaction we get first-hand feedback, can find patterns and then optimize our products to meet our customer’s needs,” says Senior Vice President of Engineering Dave de Simone. “One-on-one dialogue is an essential part of this process and helps us to understand more than just their behavior, but also why they do things a certain way, while at the same time gaining insight regarding their application-level needs. Ultimately, this leads to a much better understanding of the problem and their business needs, and results in a better solution.”

With usability testing, you have the ability to ask contextual questions, such as “Why did you click there?” and “What were you expecting?” This ability to delve into the meaning of user actions is the reason usability consultant Jakob Nielsen suggests that A/B testing will never replace live-user testing. “In many cases, a Web site’s worst problems are not issues that you’d account for in an A/B test because you wouldn’t be aware of them unless you’ve carried out usability testing,” he explained in a 2006 interview with Matt Mickiewicz “When you limit your research to the ideas you can generate yourself, you have closed your mind to all the unexpected things that users do.”

Making the Split Decision

If your challenge is one of optimization — deciding which option yields the best return — the trial-and-error method of A/B testing provides the controlled, quantitative feedback that you need to move the design through a series of successive improvements. Amazon.com was one of the early innovators with A/B testing, rolling out multiple home page versions for a short trial period. Because of the incredible volume of visitors, sometimes a few hours would provide a definitive sample size.

For A. Harrison Barnes, chief executive officer of Pasadena, Calif.-based Juriscape, A/B tests provided the tangible feedback needed for design decisions. His group tested extensively, including as many as 13 variations of a landing page. They also modified and tested banners using an A/B comparison. In one instance, changing a small portion of banner text from generic descriptive wording to promotional offers improved the click-through rate dramatically.

To determine the optimal landing page, Barnes and his team have moved to multivariable testing, an extension of A/B testing in which multiple parameters are simultaneously combined and measured rather than just one. “We defined control variables and set up an experiment,” Barnes explains. “We do statistical analysis to find out the best combination in a multivariable-testing experiment. Of course with traditional usability testing, this is not possible.”

Choosing the right test can also depend on the types of decision-makers involved in your project. For a dysfunctional team where designers and developers don’t see eye-to-eye, bringing in the voice of the customer through a traditional usability test can help them find common ground by abandoning their opinions and instead adopting the viewpoint of the customer. The customer is truly a great unknowing arbiter of design disputes.

On the other hand, if quantifiable return on investments measurements dominate your company’s decision-making processes, a statistical evaluation, such as A/B testing, can point to performance improvements that may be easier to link to dollar amounts.

The steps involved in either test vary considerably. For traditional usability tests, a small number of participants (usually six to eight) are recruited to participate. The test can be conducted in a lab setting or remotely using Web conferencing and Web cams. Before the test occurs, detailed scenarios and user tasks need to be created, along with a list of standard questions. If you outsource the work, it’s a good idea to know whether the report will include actual design recommendations or just a description of key findings.

For an A/B test, the first step is defining what will be tested and then designing a study that limits the test to one variable. Next, the team sets up analytical tracking to ensure that both versions will be measured. A/B testing is typically done in a live environment, and will run until the desired number of responses is obtained. Statistical analysis follows, and the outcome of that makes up the report.

In terms of cost, a November 2006 report by Forrester Research in Cambridge, Mass., found that the surveyed usability vendors tested 13 users per engagement, conducted tests over the course of two to three weeks, and charged $20,000 or less for this work. Project size and cost varied widely. Similar data does not yet exist for A/B tests, but a typical A/B test costs less than that amount.

While most usability studies are outsourced, more firms are insourcing A/B testing using commercial software designed for this purpose. Google very recently introduced a new Web site optimizer service that allows you to design and run A/B and multivariate tests for your Web site. The service is in a beta version now and is free to use at http://services.google.com/websiteoptimizer/. The tools, of course, are only half the battle, as well-thought-out research design is critical.

Regardless of your testing method — getting back to the McLuhan metaphor — make sure you look for regular opportunities to re-evaluate old assumptions. The value of testing is in unlearning those things that you thought you knew.

Dan Skeen is director of search engine marketing for Quarry (www.quarry.com), a communications agency in
Warterloo, Ontario.