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Web Accessibility Evaluation Tools Need People

Web accessibility evaluation tools can be very helpful; however, they do not replace the need for human evaluation. Webster's definition of "tool" as an "instrument used by a craftsman or laborer at his work" is useful in understanding the role of automated web accessibility evaluation tools.

Evaluating for accessibility requires knowledgeable human judgment. No tool alone can determine if a site meets accessibility guidelines. (However, a tool can determine if a site does not meet accessibility guidelines.) Testing tools can increase the efficiency of evaluation.

Experience with assistive technologies is required to evaluate for usable accessibility.

An analogy

Consider using spell checkers to test for typing errors as an analogy for accessibility evaluation tools. A spell checker can identify words that are not in its dictionary, and it can suggest similar words to fix the potentially misspelled word. A human must then decide if indeed the word is misspelled (correctly spelled proper names might not be in a dictionary) and if so, which is the correct spelling. Another issue is that spell checkers will not identify wrong words that are properly spelled. For example, if I type, "good text tool" when I meant to type, "good test tool" the spell checker will not identify it as a spelling error.

Alt text example

Checking alternative text (alt text) for images is good example of using web accessibility evaluation tools to increase efficiency, and of the requirement for human judgment. To meet web accessibility standards and guidelines, all images must have equivalent alt text. Images that convey no meaning, such as a transparent gif used as a spacer, should have null or blank alt text.

Most all web accessibility evaluation tools help in checking for alt text. For example, Bobby (www.cast.org/bobby) lists all images that are missing alt text. However, no tool can tell if the alt text is "equivalent" as required for accessibility. A designer could cheat most tools by putting the same "dummy" alt text for all images.

Tools such as WAVE (www.temple.edu/inst_disabilities/piat/wave) further help a human evaluator judge if alt text is appropriate. WAVE displays the alt text adjacent to the image so that you can see the image and the alt text together in the context of the page.

Bottom line

Web accessibility evaluation tools can save time and effort, but cannot replace knowledgeable human evaluators. Rather than thinking of tools as a substitute for human evaluation, think of tools as an aid to human evaluation.

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Information on this site is based on the knowledge, experience, and best judgments of Shawn Lawton Henry and other contributors. No warranties or guarantees are implied. Shawn Lawton Henry shall not be liable for any special, indirect, incidental, consequential, punitive or exemplary damages based on this information.