Usability and Quesenbery

Posted: June 2, 2010 in Uncategorized
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Looking at two articles by Whitney Quesenbery: The Five Dimensions of Usability, which is chapter 4 from Content & complexity: information design in technical communication By Michael J. Albers, Beth Mazur. and What does Usability Mean: Looking Beyond ‘Ease of Use.

The Five Dimensions of Usability are that something must be Effective, Efficient, Engaging, Error Tolerant, and Easy to Learn (84-88). So basically, if something fits all of these (inter-related) dimensions, something is very usable.

Why develop these five dimensions? Essentially, Quesenbery develops them because ‘usability’ has been used to describe too many things: a result, a process, techniques, and a philosophy (82), and while that’s all well and good, and are all important, Quesenbery wants to focus only on one of them: results.

So we have the five dimensions. Quesenbery is looking at the goals of the users. If something is Effective, it helps them meet those goals completely and accurately (83). If it is Efficient, they do so quickly and accurately (84). It may look like these two are closely tied together, and they are. But neither of them is unilaterally more important than the other. As Quesenbery writes, “In many cases a marginal increase in efficiency may be less important than completing a task correctly,” and “a perception of efficiency may be more important than actual timing” (85). Sometimes, it’s more important to be fast; sometimes, it matters more to be right.

Something is Engaging if it is pleasant or satisfying to use (86). Pretty self explanatory. Error Tolerance, how well errors are prevented or how easily they are recovered from (87), is a bit more complex. Just telling the user that something went wrong is fine, but if you don’t tell them WHAT went wrong or WHY, they are likely to make the same mistake again. Similarly, if every little mistake requires them to start over, then Efficiency and Effectiveness go right out the window. And who would enjoy using a system so frustrating?

The fifth dimension, that it be Easy to Learn, focuses both on how easy it is to start using something, and how easy it is to deepen understanding (88). It’s not hard to see how these five are inter-related. If it’s not Error Tolerant, it won’t be Easy to Learn. If it isn’t Easy to Learn, that’s not very Effective. If it isn’t Engaging, it won’t be Easy to Learn.

This is not to say that someones one or another dimension doesn’t take precedence. In fact, Quesenbery suggests that each product differs in its needs as far as these five dimensions are concerned. They are a tool, and “can be used throughout the human-centered design process for both analysis and evaluation” (90). Each product is different, as is each user (or group of users), so these five dimensions will take on different levels of importance. This seems obvious: it’s more important for a video game to be Engaging and Easy to Use than it is for it to be Efficient. And Accounting Software would be better served making it more Error Tolerant, Efficient, and Effective than Engaging. No dimension is ever going to completely disappear, but some may be reduced to very small proportions.

Quesenbery suggests that using these five dimensions, we can identify proper design tactics. We do this by setting usability goals. “A usability goal is a design objective that is unambiguous and measurable” (94), so these are specific parts of a product that fit specific criteria of the five dimensions; knowing this goal, it naturally becomes easier to meet those requirements.

Why is all this important? Quesenbery tells us that “Information is designed for people to read and use. Usability is concerned with how well they can do so. It is the measure of how successful a design is in ‘making information accessible and usable'” (99). To put it quite simply, if we want to get information across well, we need the method of transmission to be usable and user-friendly. This takes away obstacles and makes communication more clear.

So, what DOES Usability mean? According Quesenbery, a good definition would be that something was “used to understand user requirements, formulate usability goals and decide on the best techniques for usability of evaluations” (1). This is done, of course, by looking at the five dimensions of usability we just talked about. Usability is about Ease of Use, but it’s also about quite a bit more: thinking about how and why people use a product; methods of evaluation; and design focused on the user of the product rather than anyone else. (1-2).

User-centered design is important. As Quesenbery writes, “Users are satisfied when an interface is user-centered – when their goals, mental models, tasks and requirements are all met” (2). This makes people more willing and more able to use a product, and that, generally, is the idea.

Quesenbery offers suggestions for how to improve the usability of something, like providing redundant navigation to increase Effectiveness, using keyboard shortcuts and links to make it more Efficient, pleasing visual design makes it more Engaging.

As far as Error Tolerance is concerned, Quesenbery points out that “An error tolerant program is designed to prevent errors caused by the user’s interaction, and to help the user in recovering from any errors that occur” and that “a highly usable interface might treat error messages as part of the interface, including not only a clear description of the problem, but also direct links to choices for a path to correct the problem” (3). This inclusion of the user in seeing and solving the problem (and in preventing errors), increases the User-centerdness of the program, which tends to have the side effect of making a product more Engaging.

And of course, Easy to Learn. But it means more than just being easy to sit down and start using; it also means easy to improve abilities. “An interface which is easy to learn allows users to build on their knowledge without deliberate effort. This goes beyond a general helpfulness to include built-in instruction for difficult or advanced tasks, access to just-in-time training elements, connections to domain knowledge bases which are critical to effective use” (4). This way, not only is it easy to start, but it’s easy to get better.

This reminds me of a saying about chess. That it takes “Minutes to learn, but a lifetime to master.” It’s not only easy to learn, it’s pretty easy to get better. This is also the lifeblood of video games. The good games have hidden their tutorials as part of the game, letting the player have more and more control as they go, learning easily but also adding complexity as time goes on. Final Fantasy games do this VERY well.

Anyway, the important thing about usability is that it’s an iterative process. That is, you make one version, test it, and then fix the problems. Each time you go through it, it should get better. “The work proceeds in a cycle of hypothesis and evaluation, with a picture of users and design solutions to meet their needs building in richness and completeness with each iteration” (7). So the more iterations a product goes through, the better it will be.

Of course, there are limits. But discussing them would bring us to Jakob Neilsen, and I don’t want to go there right now. So I’ll just end things by saying that there ARE limits, and that usually that limit is around 5. But I’ve talked about that before, I’m sure.

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