In the inspection approach, usability specialists, users and other professionals examine usability related aspects of a user interface. Commonly used inspection methods are:
- Heuristic (Expert) Evaluation
- Cognitive Walkthroughs
- Formal Usability Inspections
- Pluralistic Walkthroughs
- Feature Inspection
- Consistency Inspection
- Standards Inspection
- Guideline Checklists
Heuristic (Expert) Evaluation
Heuristic evaluation is where a group of usability experts scrutinize a web site and evaluate each element of the site against a list of commonly accepted principles or rules of thumb. They apply their training and experience to conduct independent evaluations. Research shows that such evaluations can identify a majority of the usability problems, with the problem-identification percentage increasing as evaluators are added. The major drawback of heuristic evaluation is that evaluators, regardless of their skill and experience, remain surrogate users (expert evaluators who emulate users) and not necessarily typical users of the product. For more information see Jakob Nielsen's heuristic paper.
A cognitive walkthrough is a review technique where you construct task scenarios from a specification and get a user to role play the part of walking through the task. They act as if the interface was actually built and they (in the role of a typical user) was working through the tasks. Each step the user would take is scrutinize.
Formal Usability Inspections
This method formalizes the review of a specification or early prototype. The basic steps are to assemble a team of four to eight inspectors, assign each a special role in the context of the inspection, distribute the design documents to be inspected and instructions, have the inspectors go off on their own to do their inspection, and convene later in a formal inspection meeting. Defects found are assigned to responsible parties to be fixed, and the cycle continues.
Pluralistic walkthroughs are when groups of users, developers, and usability experts walk through a task scenario. Group walkthroughs have the advantage of providing a diverse range of skills and perspectives to bear on usability problems. As with any inspection, the more people looking for problems, the higher the probability of finding problems. Also, the interaction between the team during the walkthrough helps to resolve usability issues faster.
Feature inspections analyze only the feature set of a site, usually given end user scenarios for the end result to be obtained from the use of the web site. For example, a scenario for the training site would be to register for a workshop. The features that would be used are navigating to the workshop site, selecting a class, adding it to their shopping cart, filling out the registration form, and pressing the submit button. Each set of features used to produce the required output (a registration) is analyzed for its availability, understandability, and general usefulness.
Consistency inspections ensure consistency across multiple sub-sites from the same development effort. For example, in lower level pages, common functions should look and work the same.
Standards inspections ensure compliance with industry standards. In such inspections, a usability professional with extensive knowledge of the standard analyzes the elements of the product for their use of the industry standard (compliance with University Standards, the University Graphic Standards, the University of Minnesota Web policy, W3C specifications, etc).
Guidelines and checklists help ensure that usability principles will be considered in a design. Usually, checklists are used in conjunction with a usability inspection method: the checklist gives the inspectors a basis by which to compare the product. Usability.gov has a good set of Research Based Web Design and Usability Guidleines. Also see: Guidelines and this General Usability Checklist.