This is a very rough estimate of the distribution of the most common violations observed on homepages evaluated at Showcase.
From more common to less common:
- Low CCR, usually in the footer, sometimes in the navitagation bars, seldom in the content. On some sites this was the majority of violations.
- Link text not descriptive enough, missing link text, duplicate link text. Lots of false positives. Some instances appeared to be extra invisable links the developer might not even be aware of. Most of these were harmless. Usually, the link text was not descriptive enough because it included acronyms or abbreviations – which are, in fact, meaningful to a typical user of the site.
- Missing various tags on mouse events, on-click, keyboard events, etc. A single instance tended to generate two or three violations and magnified the apparent importance of these.
- A mix of:
- Missing labels on forms, (often the "search" form for the site!) People seem to be assuming that the pre-loaded text in the box, such as "Enter search term", would be sufficient.
- Missing headers on tables, almost always on those used for formatting purposes. This appears to be harmless is most cases.
- Missing alt text on images, mostly on decorative images that supplement the text, but occasionally on content images or nagivation elements. For example, a fairly common occuance was missing alt text on logos in the footer that are links used to share the page on facebook or twitter.