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Usability Evaluations

Usability evaluations are of two main types:

  • Design reviews - User interface or web site evaluated against design and usability guidelines
  • Usability testing - Designs testing with real users

Design Reviews

Design reviews do not involve users (so are not strictly speaking user-centred), but are very effective in reducing the number of issues that might arise during usability testing, or as a low-cost alternative to testing with users. The reviews are done by inspecting the user interface or web site and collecting screenshots of potential usability issues. (A rating scheme can also be used where a number of evaluations are to be compared.) These are then compiled into a prioritised report showing each issue, explaining its possible impact on usability and recommending alternatives.

While most reviews are done on existing systems, it is possible to review designs while they are still on paper or in rough prototype form. Early reviews can have a dramatic effect in reducing the cost of development and delivery schedules.

Be aware that the effectiveness of design reviews is dependent on the experience of the reviewer. With over 30 years experience in interactive systems, involving scores of design reviews, we are confident in our ability to provide high-quality and cost-effective reviews.

Woman at desk with laptop while man observes

Usability Testing

The most important difference between design reviews and usability testing is that the latter is done with real users. However, there are quite a few potential variations:

Prearranged versus user-generated tasks
Most usability testing is performed with prearranged tasks, especially where comparisons are to be made between sessions. However, in some situations it can be more telling for users to choose tasks that are important or problematic for them.
Quantitative versus qualitative focus

While quantitative test results (primarily time to complete and number of errors) are the most useful in comparing alternative designs, qualitative inquiries can help to establish users' overall reaction to and understanding of a design. This can be particularly important in the development of novel products or services.

Natural versus lab environment

The choice of testing environment can sometimes be a difficult one, but with portable equipment we can cater for both natural and usability lab situations. Testing in situ can be particularly useful for consumer products and services, where many external factors could affect their success, for example as in home shopping or media services. On the other hand, usability labs make it possible to have a number of unseen observers present and provide a more consistent setting for video recording.

Video recording

The facilitator's notes are the primary source of information for the usability report, but video recording has an important role to play in selling usability within a project team or in the larger organisation. As mentioned above, a lab setting will provide the most consistent results, but recordings made in natural environments can add an extra dimension for those not involved in site visits. We use a high-quality digital process for recording, which costs no more than the low resolution methods still commonly in use.

Costs

Design reviews typically range in price from £900 to £1600, dependent on the size and complexity of the product or service being reviewed and on the amount of detail required. By comparison, usability testing generally starts at about £1600 without video recording, but user incentives and lab rental must be added to this. Extensive usability testing of a large site or complex product (say with about 20 users) would cost in the region of £3600 (plus user incentives and lab rental). All prices are exclusive of VAT.

The information provided here is for general guidance. Please contact us to discuss your requirements in detail.

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