In every book I read abour design, they always present them at different level: IA adress the structure ( ex: site design ) and UI work in the detail ( ex: page design ). So both have to predict and measure users actions.

PS: In IA, you can measure users action ( or reaction ) on your prediction with card sorting.

PS: I'm no expert in IA. I just read the same book as everyone: "IA for www".

Posted by: Richard Lehoux on December 18, 2002 09:59 AM

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Mac said: "IA predicts user actions while usability measures user actions."

Yeah, it's an important distinction -- it's design vs. critique -- and one reason the two professions seem to keep talking past each other.

Granted usability _engineering_ ideally does involve the design process (including doing stuff that looks a lot like IA, interaction design and UI design), but on the whole, the self-described "usability" profession has tended to focus on the testing end of things.

In part it's because traditional usability folks often came from cog-sci backgrounds and never got a background in design matters. In contrast IAs (however you want to define them) often came from a "creative" (in the sense of creating things) background, whether it was visual design, writing, organizing materials etc. So they tended to focus on designing things first, then testing them.

Usability (testing) folks have too often abdicated the design to someone else and only offer critiques -- and ending up marginalizing themselves. At best these folks offer usability guidelines for design, but that ain't the same thing as actually getting your hands dirty and _doing_ the design work.

Personally, I think you need both design and critique skills. A designer who's done usability testing is a stronger designer for having internalized the lessons learned -- and more likely to get the design right the first time. A usability tester who has design skills will offer much more cogent analysis and recommendations. They'll also be much more aware of the real-life design balances that always need to be struck.

Otherwise it's like coaching a sport you've never actually played yourself. You don't have to be a master of it to coach, but you do need to have experienced it.

Posted by: George Olsen on December 18, 2002 02:33 PM

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