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Medical Library Association Encyclopedic Guide to Searching and Finding Health Information on the Web

edited by P. F. Anderson and Nancy J. Allee

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Overview and Information: Site Accessibility and Usability

The design of accessible web sites is, of necessity, a series of compromises. There is no one-size-fits-all perfect design equally accessible to all persons in the world. This page describes the choices made in designing this web site, and the reasons for these.

Accessibility Standards

This site was designed to adhere to the standards and guidelines recommended by the World Wide Web Consortium (W3C), in Web Content Accessibility Guidelines 1.0. This was tested with Bobby, and passed at the AAA level. It is recommended by those guidelines to design using cascading style sheets (CSS). The decision was made to not use CSS for this first version of the site because of the desire to support outdated browsers and computers, some of which do not read or properly interpret CSS. Instead a very minimal HTML design was used. Compatibility with older browsers and computers was tested with the Web Page Backward Compatibility Viewer.

Navigation and Skip Tags

All navigation and header information can be skipped by text reader software programs with a link to Page Content. Use of tables and graphics were kept minimal to reduce load time, so the skip-tag would be most effective.

Navigation links are provided on each page across the top and bottom of the page. Column-style navigation is avoided to minimize load time, maximise use of screen space, and minimise required mouse movement between links.

Text and Layout

Centering was avoided because of the potential difficulties it causes for persons with low-vision using screen enlargers. All content is organized top to bottom and left to right, with predictable layout patterns used consistently throughout the site.
Text Size
Text size can be changed at will, and defaults to the user preferences under most circumstances. The most notable exception is that the font size is reduced one level smaller than the surrounding text for the navigation links repeated on every page.
Font Selection
Because computer monitors usually have a lower resolution display than print (75 dpi as compared to a standard 300 dip or higher), it is recommended to simplify the font display onscreen by using non-serif fonts. The reverse is recommended for increasing readibility of print materials. Font preferences can be specified in the user preferences for your browser, however persons using computers in public libraries, general computing sites, or community centers may not have access to these controls. For this reason, the website specifies non-serif fonts throughout, but leaves font size up to the viewer. You may override this if you choose, again by modifying the preferences settings on your own computer.
Fluid Page Layout
Our page layout supports resizing of browser windows. We don't use frames for layout, and use layout tables minimally, and only where content cannot be provided coherently without them.


Color Support for Learning and Navigation
Since this web site is intended to support the instructional resources in the printed book, and may also be used for individual and group instruction, the design of the site incorporated suggestions for education web sites such as the use of color to define sections of the site.
Impaired Color Vision
All color combinations in this web site were tested for readability by the color-blind with the Vischeck tools.
Non-Dithering Colors
To support the use of this web site by older computers and monitors, all text and background colors were selected from non-dithering hues, and were tested on a 256 color display and a grayscale display.
Glare, Eye-Strain, and Scotopic Sensitivity
Computer users can experience eye strain both from too little contrast between the text and the background and from too much contrast. The rule of thumb is for a 70% difference in the intensity of the two colors selected. Black text on white gives a 100% difference. Some individuals prefer more than 70%, others prefer less. The article Colour & Contrast Accessibility Issues for the design of e-learning materials from TechDis describes a variety of color and contrast preferences for various populations. Use of any color remains potentially problematic for persons with impaired color vision or color sensitivity. Use of no colors, with the usual black text on white background, creates challenges even in printed text for persons with scotopic sensitivity, ADHD, migraineurs, dyslexics, and others. This difficulty can be heightened by the projected light of the computer screen, making glare and distortion a greater problem. The selection of a pale yellow background with dark grey text was a compromise solution to address the need for sufficient contrast to prevent eyestrain in persons with normal vision while reducing the contrast to meet the needs of persons with different visual and learning needs. We acknowledge that there is no one color combination which will meet the needs of all persons. Colors do not display identically on all monitors. The colors selected for this site are all intended to display as pale colors, and will be pale on most computers. If they appear more intense on your computer, it may be possible to adjust your monitor settings.

More Information

For more information about accessible web design, please refer to: Web Accessibility for Health Websites, by P. F. Anderson, especially the resource list at the end of the essay.

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