Geography Reference
In-Depth Information
2. Usability studies
The term usability is defined as “the effectiveness, efficiency, and satisfaction with which
specified users achieve specified goals in particular environments” [5]. Satisfaction
quantifies subjective users' impressions dealing with such indicators as operability and
learnability of a given task. Efficiency and effectiveness metrics are objective performance
measures of speed and accuracy. [6]
Nielsen [7] defines usability as a quality attribute that assesses how are user interfaces easy
to use. Usability can reveal qualities of the product as well as lack of its functionality, which
usually arises during the design phase of a product. [8] The assessed product can be an
image, web page, text or a map. To be able to derive qualitative or quantitative measures of
the user experience (usability), a number of evaluation methods is possible to use. Li et al.
[9] mentions these methods of usability evaluation:
focus group studies,
interview,
direct observation,
think-aloud protocol,
retrospective think-aloud protocol,
screen capture,
eye-tracking.
Each method has its advantages and disadvantages. Frequently a combination of methods is
used in the research. For example, see [10, 11, 12].
The method of focus group studies and interview are based on direct contact with the user.
They are based on a targeted questioning and recording of discussions and responses of
individuals or groups.
The method of direct observation leads to the detection of subject's behaviour in its natural
environment without any interference by the observer. For observation various technical
utilities, especially recorders, cameras and camcorders, are used. Direct observation
sometimes leads to problems in professional ethics, especially when observed people are not
acquainted with the fact that they are the subject of observation.
A frequently used method is "Think-Aloud". Its principle lies in the verbalization of the
process performed by the user during solving a specific problem. Participating test subjects
verbally describe the process of solving specific tasks and also their feelings [13]. This
method is very quick and inexpensive, nevertheless, participant is not aware of all cognitive
processes, and not all processes can be simply expressed in words. This method is very
subjective in the term of observed subjects, who describe their experiences, and also in the
term of the evaluation of their response. Detail usage of this method is discussed by
Somersen [14]. Similar to the "Think-Aloud" method is a retrospective variant, when the
subject describes a workflow after the task is completed.
The screen capture method of usability study was in the field of cartography and GIS used
for example in Haklay et al. [15]. They assessed the usability of GIS software using
