The Usability Process in Computer Science

Copyright 1995 Richard Halstead-Nussloch
All rights reserved

The usability process is an extremely important aspect of computer human factors. Because the purpose many people purchase computers is to use them, a process to ensure they are usable is always key. Many different approaches have been defined for defined for performing usability work. Most of them that I recommend have these elements: Identifying usability requirements This step is best done in collaboration with product planners. It is best done up front before any design or code is begun. The requirements stage is the entry point for usability processes that link to the business process, i.e., those that incorporate user-centered design, contextual design, focus groups, quality management, and management of customer satisfaction.

Establishing usability objectives

This step is best done through compilation or summary of the usability requirements. This stage is the entry point for usability processes that are tied to technical development. Usability objectives need to be measurable. Standard objectives include (but are not limited to):

Relating usability measures or metrics to the usability objectives

This step is best done through setting up a table showing how measurement of the objectives will be done. In the left column, place the objective. In the right column, place the measure or metric. Standard metrics and measures include:

Setting Criteria or Design Points on the Usability Measures

This step is extremely important, as the criteria determine when the design work is complete. The criteria are set to identify when customer needs are met.

Designing iteratively

This step is repeated until the design tests out as meeting customer needs and criteria. This is an opportunity for synergistic teamwork among developers, user interface designers, coders, marketing, and even users and customers.

Testing

The designs, prototypes, product components, products, documentation, etc. should be tested. Testing should be done early and often and be an integral part of all stages of development. Once the product is developed, the final integration or acceptance test should incorporate usability.
Task-scenario-based testing is most often the best choice. In this kind of testing, typical task scenarios are developed, and actual users evaluate the system's usability through performing those tasks.

Surveying customer satisfaction and performing post-install follow-up

Once the product is released, usability questions should be a part of the customer satisfaction survey. A post-install follow-up should examine how well the original usability requirements were met, and assess any impacts of any usability changes or trade-offs made during development.

A Sample Usability Plan
Computer-Based Training for Children Concerning Care of Pet Rodents

System Overview

For many children, pets are an important part of growing up. Pets provide an opportunity to view the cycle of life, and provide opportunities for young people to take on responsibility of a fulfilling, meaningful nature. Popular pets now include cats, dogs, and birds, and rodents are growing in popularity. These include hamsters, mice, rats, gerbils, etc. Unfortunately, market research shows pet rodents are not as well cared for, all things considered, as are birds, cats, and dogs. This research also shows that lack of knowledge on the part of children and adults is a primary cause. Furthermore, children appear motivated to care for their rodent pets.
The system to be evaluated in this plan is a multimedia instructional title with the purpose of providing engaging instruction for children in the care of pets, particularly small rodents.

Usability requirements

The primary target audience and users include children, aged 5 to 12, with children aged 13 to 17, and parents comprising a secondary audience. The usability of the system should support ease of use, not get in the way of and support learning, and make the user comfortable and satisfied. Usability requirements will be documented in terms of user interface objects and typical user tasks that our title must support.

Usability objectives

The user interface and usability of the title should be: The user interface and usability must be evaluated as good as or better than the following competitive titles, which serve as a baseline to our title:

Usability metrics and measures

Time-on-task, errors, assistance request, and task flow through the task scenarios are standard measures that will be used throughout the usability process. Comfort and satisfaction questionnaires will be used to assess those factors. Specific metrics for each objective are covered in the next section on usability criteria.

Usability criteria

Two kinds of criteria are established:

1) Competitive criteria

Our title must have the same or better usability than the competitive titles listed above. Usability levels for those titles are described in company confidential report xyz.

2) Product criteria

Our title must meet specific criteria defined as a part of the overall quality process for our development. Criteria specific to this product include:

Iterative design plan

Usability staff and user-interface designers will work closely with planners, requirements experts, and coders to iteratively design the user interface. We will start from the company guidelines and conventions, and enhance these standards to meet the usability needs identified in the requirements phases. All issues and conflicts will be arbitrated through a usability evaluation employing representative customers and users.

Usability testing

Usability testing and evaluation will be performed as a part of all testing done as the company quality process. This includes concept, prototype, unit, system, and install testing. It will employ the conventional task-scenario based testing using actual users/customers. Conventions for testing are described in company practice manual PQR.

Post-install activity and customer satisfaction survey

Usability staff will review trouble reports and calls to the support line for usability problems. Usability staff will support marketing and planning in the customer satisfaction survey required as a part of the company quality process. Pertinent data, conclusions, and recommendations will be forwarded to all appropriate company functions.