Usability of Geospatial Information

A number of possible definitions of usability are available in the literature of geospatial information, and the needs of spatial data usability have been compared and contrasted with the broader data-related activities of providers and users of [Page 3003]geoinformation. For example, one official definition of usability is given by the ISO 9241–11 standard on Display Screen Regulations, Use of Ergonomics for Procurement and Design. In this definition, system usability consists of the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency, and satisfaction in a specified context of use, where

• effectiveness measures the accuracy and completeness with which users achieve specified goals,
• efficiency measures the resources expended in relation to the accuracy and completeness with which users achieve goals, and
• satisfaction measures the freedom from discomfort and the positive attitudes toward the use of the product.

Usability elements outline the features and characteristics of the product that influence the learnability, effectiveness, efficiency, and satisfaction with which users can achieve specified goals in a particular environment. The context of use determines the types of users, tasks, and equipment and the physical and social environments in which a product is used. Therefore, a system consists of users (the people who interact with the products), equipment (hardware, software, and materials), tasks (activities required to achieve a goal), and a physical and social environment for the purpose of achieving particular goals.

Usability has also been defined as a set of attributes that bear on the effort needed for use, and on the individual assessment of such use, by a stated or implied set of users (see ISO 9126). This definition differs from the ergonomics-based definition in that characteristics other than efficiency and effectiveness are also seen as elements of usability.

Nielsen, concerned with software usability, sketches a broader context he calls system acceptability. One aspect of it is usefulness, which pertains to whether the system can be used to achieve a desired goal. Therefore, it is possible to break usefulness down into utility and usability—utility denoting the question of whether the functionality of the system in principle can do what is needed and usability denoting the question of how well users can use this functionality.

It is hard to isolate a core set of fundamental techniques that clearly distinguish data usability from any single-component discipline; in some ways, it is a uniquely powerful combination of individual techniques that characterizes the field. In summary, data usability might be identified as an umbrella term consisting of several elements aggregated into several groups:

• Marketing: added value, benefits, costs, novelty, services provided, and satisfaction
• Quality: authoritativeness, guarantee against error, integrity, metadata, reliability, validity, and utility
• Software and tools: human computer interaction, standardization, integration, searchable, and interface
• Human perception/cognition: authoritativeness, decision type, interestingness, novelty, popularity, satisfaction, trust, user skill levels, familiarity, interpretation, and visualization
• Applications: aggregation levels, type, exclusiveness, visualization, integration, decision type, use with models and algorithms, availability, and accessibility

Each individual category can be discussed in light of specific user groups and/or applications. For example, in the marketing category, cost is a very common and often a very important element and plays a large part in usability. In the applications group, availability and accessibility also determine the use of data. Moreover, it is important to realize that elements such as accessibility and cost of spatial data can vary among different countries and cultures. Another example is the update frequency. To decide on the desired update frequency, users should be asked to define the tolerable difference between decisions made and the time frame for future decisions.

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