today I want to introduce you to the WCAGs 2.0 - the web content accessibility guidelines and how to evaluate an existing web site using heuristic evaluation methods as described by Jacob Nielsen.
Web Content Accessibility Guidelines [1]
These guidelines are a good basis to work on when designing web pages for different groups of users including for example visual impaired people and more or less describe what to consider. Important to know is, that these "principles" are just recommendations and not rules.
The W3C consortium describes the WCAGs as follows:
Web Content Accessibility Guidelines (WCAG) 2.0 covers a wide range of recommendations for making Web content more accessible. Following these guidelines will make content accessible to a wider range of people with disabilities, including blindness and low vision, deafness and hearing loss, learning disabilities, cognitive limitations, limited movement, speech disabilities, photosensitivity and combinations of these. Following these guidelines will also often make your Web content more usable to users in general.These guidelines cover a wide range of different topics like how perceivable or how understandable a site is or how good the interoperability is when just using a keyboard. It would be too much now to go into detail but I want to list just a few principles which are the most important ones for me:
- providing alternatives for all elements: this means, providing ALT attributes for images or video content
- the contrast between the foreground and background should be a good one to make it easy to differ between real information and background info
- the UI should be navigable using a keyboard only - so setting the TabIndex attribute is important
- when designing forms, provide the "name" attribute for the input fields and put them into relation with labels using the "for" or "label" attribute
- when structuring web content, use the H1-H6 elements to do so, 'cause usually screen reader applications rely on them
Heuristic evaluation [2]
Heuristic evaluation is, according to Jacob Nielsen, a discount usability engineering method for quick, cheap, and easy evaluation of a user interface design.
Heuristic evaluation works the following way:
- find "principles" - so called heuristics on which the evaluation should be based on. In our case, these heuristics would be the WCAG principles. Such principles are usually defined by a group or a single person, commonly used and good recommendations to follow but should not be considered as fixed rules
- according to these principles, evaluators - who are usually usability experts - go through the whole interface of the application step by step and take notes, when the UI does not consider one of the principles. Usually, a good number for the amount of usability experts to use is between 3 and 6, 'cause one expert will only find 35% of all the problems. 5 experts will find about 75% of the existing problems.
- after each evaluator has finished his process, they all meet together and compare their notes. Based on these notes, they rate the problems using the "severity rating". Therefore, each problem is assigned a number from 0 to 4, whereas 0 means, that there is no problem and 4 means, that it is a complete mess and a usability catastrophe
- at the end, these results are summarized and presented to the developer team or the customer
Heuristic evaluation is a quick method for reflecting your UI and finding major usability problems according to various heuristics. These heuristics can be the WCAGs as well as other defined principles.
[1] ... WCAG web site [http://www.w3.org/TR/WCAG20/]
[2] ... Heuristic Evaluation [http://www.useit.com/papers/heuristic/]
[3] ... How to Conduct a Heuristic Evaluation [http://www.useit.com/papers/heuristic/heuristic_evaluation.html]
No comments:
Post a Comment