Customization of UIs and Products

by Jakob Nielsen on August 17, 2009

Summary: Websites that let users customize the UI have the same measured usability as regular sites. Sites for customizing products, however, score substantially worse due to complex workflow.


Web-based customization is not new. As far back as the mid-1990s, people have touted customization as both the Web's destiny and the panacea to all business ills. After filtering out the hype, it's clear that Web-based customization can, in fact, be utilized to benefit both businesses and users…if implemented properly.

Customization's usefulness is obvious for many applications. Still, there are countless tales of companies investing heavily in customization only to find that users rarely — if ever — customize. There are also numerous studies that tout users' desire for customization, but (as we know) what users say is often at odds with what they actually do.

Ultimately, for customization to succeed, you must have a business need for it and identify realistic hard and soft benefits to offset the expense of implementing it correctly.

Customization vs. Personalization

Although not commonly used, we could adopt the term "individualization" to refer to cases in which the user experience is adapted to each individual user's needs. In the early days of computing, everybody got the same thing. Similarly, in the Web's early days, all pages always looked the same, no matter who was visiting.

Today, designs are often adapted to individual users, so that different people see different screens both in applications and on websites. There are two main ways to individualize the user experience, depending on who initiates the adaptation:

  • Customization happens when the user tells the computer what he or she prefers to see. Examples include:
    • Changing a news site to display the user's hometown weather forecast upon future visits to the homepage.
    • Changing an automobile vendor's site to display a particular car model with specific color and feature options, along with the customized car's list price. Most auto sites now feature such configurators.
  • Personalization happens when the computer modifies its behavior to suit its predictions about the current user's interests. Examples include:
    • An intranet portal employs role-based personalization to show management-related features only to users who are registered as managers in the HR database.
    • An e-commerce site displays a list of the user's last five orders to make reordering the same products easy.

Our current research doesn't cover personalization. Instead, it focuses on two types of customization:

  1. Interface customization: Functionality that lets users customize their online experience by adapting the user interface to suit their preferences.
  2. Product customization: Functionality, such as a configurator, that facilitates customization of offline products, including custom-manufactured products.

Customization is not limited to websites. For example, the prevalence of "app stores" and ringtone downloads attests to the attraction of customization for both advanced and simple mobile phones. Even so, we limited our current research to testing customization on the Web.

User Research

To assess the usability of customization functionality on the Web, we conducted a usability study with 24 users interacting with 7 sites that incorporate customization: 3 websites that let users customize their online experience (interface customization) and 4 websites that let users customize an offline product (product customization).

Interface Customization Sites

  • iGoogle
  • My Yahoo!
  • Pageflakes

Product Customization Sites

  • Custom Ink (custom t-shirts and other wearables)
  • Action Envelope (custom envelopes)
  • [me] & goji (custom cereal)
  • Tiny Prints (custom invitations and announcements)

On each site, we asked users to perform typical customization tasks, such as:

  • Add a to-do list to your page
  • Take a gadget off the page
  • Add a feature that posts daily pictures of cats
  • Assume that your business is moving and you need to print 500 announcements on a budget of $600

Business Benefits of Customization

When deciding whether to add customization features, it's important to first define your business objectives and then determine how customization might help you meet them. Following are some business benefits of Web-based customization.

Increased Traffic and Loyalty

In the case of iGoogle and My Yahoo!, customization is a value-add to an existing business model. Ideally, offering customization increases the number of users who will visit the site and choose it as their start page, thereby increasing page impressions and ad-based revenues.

In 2008, for example, iGoogle reportedly accounted for 20% of visits to Google's home page. As well, users who take the time to create their own custom Google or Yahoo! homepages are more likely to engage with site offerings such as Web-based e-mail and search.

Reduce Operating Costs

For businesses such as Action Envelope, there's an operational incentive to not only place catalogs online, but also to provide customization functionality so that users can configure and place their orders online as well. Without the Web, such companies would have to print and mail catalogs and maintain a large sales staff to reach the levels they can with Web-based customization.

Cast a Wider Net

Traditionally, geography limited businesses that required customer interaction to determine the product. Today, that's not the case. Tiny Prints, for example, lets users create custom announcements and invitations online. Before the Web, customers typically achieved this only by visiting the printers, where they'd select paper, fonts, and ink colors, and then examine proofs, make corrections, and so on. The same was true with custom cereals: you could create your own at a natural foods market, perhaps, but not everyone lived (or lives) near such stores. The ability to offer customization online makes such individualized products available to the masses.

Usability Challenges on Customization Sites

Our study looked at sites with and without customization to see whether there are any marked usability differences. We also separated interface customization sites from those with product customization. Interface customization task success matched that on non-customization websites, with an average completion rate of 83%. However, product customization sites averaged only 66% task completion — a significant gap.

In our post-task surveys, users generally reported feeling more lost and less in control on the customization websites, as the following (averaged) ratings indicate:

  Non-Customization
Sites
Customization
Sites
Feeling oriented 60% 53%
Feeling in control 66% 60%

Having users feel less in control on customization sites is particularly unfortunate, given that the goal of customization is to cater more precisely to each user's needs. Current customization user experiences have a tendency to get in the way, rather than empower users and make them feel appreciated.

The complexities of customization impact both task success and perception of the site.

For interface customization, the main problems relate to discoverability, findability, and comprehension — that is, getting to the customization in the first place, and then finding and understanding the available options. To reward first-time users with an early success experience, sites should better explain features and provide fast-tracked workflows. In our study, for example, iGoogle's promise to create a simplified personal homepage "in under 30 seconds" was successful and encouraged users to start experimenting with the service.

For product customization, poor findability caused even more problems: it was responsible for 45% of the many task failures on these sites. Overly complex workflows also caused many problems. Users frequently missed steps or misunderstood what was required to successfully design their own products. For example, one site asked users to specify font sizes in units that made no sense to the average person, resulting in a frustrating trial-and-error with different numbers. This particular problem was exacerbated by the unfortunate choice of a default size that was too small for almost all users.

The Importance of Good Defaults

Despite its benefits, many users don't avail themselves of customization features. Users exhibit a strong bias toward simply getting things done on a website, rather than spending time fiddling with preference settings.

It's too easy to resolve a design debate by simply offering all the possible options as preference settings and letting users decide the interface for themselves. Often, it's better for users if the design team decides on a single good, coherent user experience. Customization options should be reserved for those features that offer substantial user benefits, thereby compensating users for the time spent on customizing the UI rather than on accomplishing their tasks.

In any case, some users won't customize no matter how easy and rewarding you make the customization interface. It's therefore imperative to retain a good default design for non-customizing users.

Customization: Effective When Implemented Correctly

None of the sites we studied offered gratuitous customization; each site benefited from its customization and offered great benefits to users who took advantage of it. In observing users interacting with these sites, we witnessed both best and poor practices, which we've distilled into 46 guidelines for customization design. These guidelines outline the design principles that you should follow to ensure that your customization efforts provide an effective, efficient, and satisfactory experience for your users.

Customization is complicated, both technologically and design-wise. To get a user from blank slate to fully customized interface or product takes exceptional design skill. It also requires cooperation among multiple groups to assemble, organize, and architect a usable customization path. Customization isn't something you can throw together in a couple weeks, and businesses who approach it in that manner are risking their reputation and revenues.

Full Report

93-page research report with 46 design guidelines is available for download.


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