Effective
Effectiveness refers to the ability of users to perform tasks completely and
efficiency
deals with
how quickly
a task is carried out. An effective user
guide should, therefore, provide correct information which will allow the
user to complete tasks successfully.
Efficient
Efficiency is the speed at which users can perform their tasks accurately. In
the ISO 9241 standard, efficiency is defined as the total amount of resources
expended in performing a task. Quesenbery makes the point that in order
to fully appreciate efficiency, it is essential that the notion of a task be ap-
proached from the point of view of a user. Whereas a system designer
might treat an interaction between a user and a system as a series of small
tasks, these tasks are grouped together by users to form one large task.
Thus, the procedure for connecting a new printer to a computer might
consist of small, efficient tasks such as connecting the cable, installing the
drivers, calibrating the printer etc., but if the total time needed to complete
all these tasks is greater than that the amount of time a user is prepared to
spend, the overall performance of the system is inefficient. In the case of
user guides, the information should be clear, digestible and concise. If users
have to grapple with unwieldy constructions or ambiguous instructions, the
efficiency of the system will undoubtedly suffer.
Engaging
An interface or system is engaging if it is pleasant and satisfying to use. An
engaging system will hold a user’s attention and make using it a rewarding
experience. This characteristic can be affected by such things as the visual
design of the interface where the readability of the text as well as the type
of interaction can change a user’s relationship with the interface and system.
The way in which information is chunked also plays a role in how engag-
ing an interface is and helps maximise the resources of a user’s short-term
memory.
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