Introduction/Methodology: Accessibility data generated with Bobby

For each of the 13 four-year University of Wisconsin campuses, I collected three sets of accessibility data: (1) the campus homepage and the first layer of hyperlinked pages, (2) the library homepage and the first layer of hyperlinked pages, and (3) homepages of academic units (schools, departments and programs).

I used the downloaded version of Bobby, which is an accessibility validator created by the Center for Applied Special Technology.   Bobby was created to assist people in checking the accessibility of their web pages.  I used it in this study to evaluate the various sets of campus pages.   For each page checked, Bobby provides information pertaining to the type, number, and location of accessibility errors--both minor and major ones. Bobby also issues a summary report for each set of web pages. Web pages that contain any major ("high-priority") error do not receive Bobby's approval.

To the best of knowledge, this is the first study in which Bobby has been used to systematically compare the accessibility of web sites at educational institutions. A cautionary note is in order concerning  the interpretation of the numerical data reported here: As Bobby's creators freely admit, their product is not a perfect tool. While Bobby checks for compliance with the W3C-WAI Web Content Accessibility Guidelines and Techniques, it actually checks for compliance with only a subset of these.  Thus, in some cases, Bobby produces falsely positive (error-free) findings. Conversely,  as I found out during this study, Bobby occasionally produces falsely negative results. For example, pages that, at the very beginning, provide a "text-only version" link will not pass Bobby's muster--no matter how perfectly accessible the text-only version may be.

In my opinion, one particular shortcoming of Bobby is its inability to distinguish between degrees of impact between different manifestations of the same error.  For example, a bullet icon without alternative text registers as equal in status (i.e., as having "high priority") to that of an image (also without the ALT tag) that is packed with crucial information. Furthermore, Bobby classifies certain types of accessibility errors as equal in severity even if the barriers they constitute differ to a significant degree. E.g., the lack of alternative text associated with a purely decorative image registers as an error equal in need of correction to the lack of frame labels in multi-frame pages.

In light of the above problems, the data presented below can only be interpreted as rough measures of overall site accessibility.

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Created by Axel Schmetzke, Library, University of Wisconsin-Stevens Point.
Last updated 7-9-99.
Comments are welcome!

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