Civil Engineering Reference
In-Depth Information
A task that has an easy and smooth work flow is simply more interesting and more
satisfying to perform.
Karat (1997) elaborated further on the importance of usability. She noted that usability
engineering has many direct and indirect positive effects for an organization. It is like the
quality movement in manufacturing. Because of the increased
TABLE 2.4
Increased Usability Has Many
Beneficial Effects on Systems Development
(Karat, 1992)
Product design and product performance will improve.
User satisfaction will increase.
Since usability errors can be detected much earlier in the systems development cycle, the
development time and the development cost for the interface will be reduced.
As a result of the improved software design, sales and revenue will increase.
Because interface is easier to handle it will take less time to train employees.
There will also be reduced maintenance costs, reduced personnel costs, and improved user
productivity.
focus on the user, there is a better understanding of user needs. As an added benefit, the
definition of the product or the software improves (see Table 2.4).
Take, for example, software maintenance. Studies have shown that 80% of
maintenance costs are spent on unforeseen user requirements; only 20% are due to
software bugs. If usability engineering can identify and resolve a majority of user
requirements prior to product release, the organization will accrue substantial benefits
and avoid future costs. It is best to conduct usability studies early in the product
development life cycle in order to provide feedback on product design and performance.
An example: Karat (1990) reported on the design of a system that was used to
complete 1,308,000 tasks per year. She studied the software for this task and managed to
improve the usability, so that the task performance time was reduced by 9.6 minutes per
task. The first-year benefits due to increased productivity could then be calculated:
1,308,000×9.6 minutes=209,280 hours, which corresponded to a cost savings of
$6,800,000. The usability testing and the related costs amounted to $68,000. Therefore
the cost-benefit ratio could be calculated as 1:100 for the first year of application.
2.5
DISCUSSION OF COSTS AND BENEFITS
The two case studies have illustrated the costs and benefits of ergonomics improvement
in industry and usability improvements in human-computer interaction. In the industrial
case it was difficult to attribute the improvements in productivity to ergonomics alone.
There were many other simultaneous changes in the manufacturing plant, and it can
therefore be argued that industrial implementations of ergonomics are not so well
controlled. Nevertheless, most of the interviewed employees agreed that the
improvements in productivity were primarily due to the improved illumination system.
As a result of the improvements, operators could see what they were doing, and many
quality errors could be avoided.
