One possible way to evaluate the usability of navigation icons may be to determine the amount of interaction Web site visitors have with them. Common sense says that the higher the click rate, the greater the indication that visitors are attending to them. Of course measuring click rate would not indicate that visitors were understanding the intended purpose of the navigation icons, but use of them would presumably mitigate that. The reason is that the more often a visitor uses a navigation icon, the more opportunities there would be for the visitor to learn its purpose.
At the time of this writing, I know of three tools that could provide an accurate measure for the click rate of navigation icons. Each is marketed as an evaluator of Web site usability.
They are CrazyEgg, ClickTale and Google Web Site Optimizer. These tools essentially work the same way. On a test Web page, a “heat map” is set up that tracks where on the page a visitor clicks. Clicks to navigation icons embedded in such a page can be tracked. A high percentage of clicks to a navigation icon or icons, compared to the percentage of clicks to other elements of a test page, would indicate that visitors are attending to them.
I plan to use the Google Web Site Optimizer because it appears it will meet my intended purpose, it is free, and it is simple to set up. Future blog posts will describe the set up process and the related test results.
Note: No endorsement is intended or implied for the tools listed above.