[IxDA Discuss] Usability is more than...

[Todd Zaki Warfel]

On Mar 4, 2008, at 12:01 PM, Jeff Howard wrote:

> My entire context for usability has been as an evaluation tool to  
> identify design elements that are initially confusing or that  
> involve a high error rate for some ergonomic reason.
[...]
> That seems to frame usability as an analog for design itself[...]
>
> Without starting a holy war, I'd be interested in opposing  
> perspectives on what constitutes usability.

Jeff, great question. My first response to you would be how did you  
arrive at your view/perspective on usability? And no, it's not a trick  
question or trap.

According to the ISO, usability is defined as ""effectiveness,  
efficiency and satisfaction with which a specified set of users can  
achieve a specified set of tasks in a particular environment."

While I would personally say that it's really goals rather than tasks,  
I'm not going to get into a semantic debate here on this one. It's  
close enough to get the point across.

While you're correct for the most part about it being an evaluation  
tool/method, in it's most rigid sense, at my company we couple  
usability/research with design. I cannot speak for other firms, but  
that's the way we operate—one informs the other and hold a symbiotic  
relationship to each other.

As for what usability measures/evaluates, well, in my opinion  
"effectiveness, efficiency, and satisfaction" consist of:
Error frequency, prevention, and recovery—how often are errors made  
and how well does the system support error prevention (first) and  
error recovery (second).

Efficiency and productivity—how does the system support or hinder the  
person from doing their job or accomplishing their goal/activity?

Learnability—is it immediately intuitive? If not, then how quickly can  
someone learn to use the system and maintain that knowledge?

Satisfaction—to what degree do they like/hate using the system?

I'd be interested to hear what others have to say as well.


Cheers!

Todd Zaki Warfel
President, Design Researcher
Messagefirst | Designing Information. Beautifully.
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