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13 Evaluation (13.3 Types of Evaluation (a. we classify evaluations into…
13 Evaluation
13.3 Types of Evaluation
a. we classify evaluations into three broad categories, depending on the setting, user involvement and level of control. these are:
i. Controlled settings involving users (examples are laboratories and living labs): users' activities are controlled in order to test hypotheses and measure or observe certain behaviours. The main methods are usability testing and experiments
ii. natural settings involving users (eg. online communities and products that are used in public places): there is little or no control of users' activities in order to determine how the product would be used in the real world. the main method used in field studies
iii. any settings not involving users: consultants and researchers critique, predict and model aspects of the interface in order to identify the most obvious usability problems, the range of methods includes inspections, heuristics, walkthroughs, models and analytics
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c. a key concern for deciding on which approach to use is how much control is needed in order to find out how an interface or device is used,
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13.1 Introduction
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b. Evaluation focuses on both the usability of the system (eg how easy it is to learn and use) and on the users' experience when interacting with it (eg how satisfying , enjoyable or motivating the interaction is)
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d. Evaluation usually involves observing participants and measuring their performance - in usability testing, experiments or field studies
e. There are other methods however that do not involve participants, such as modeling user behaviours
f. The level of control on what is evaluated varies, sometimes there is none, such as in field studies and in others there is considerable control over which tasks are performed and the context, such as in experiments
13.2 The Why, What, Where, and When of Evaluation
13.2.1. Why Evaluate
a. As the Nielsen Norman Group notes, "User experience encompasses all aspects of the user's interaction...
- the first requirement for an exemplary user experience is to meet the exact needs of the customer, without fuss or bother,
- next come simplicity and elegance, which produce products that are a joy to own, a joy to use"
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13.2.4. When to evaluate
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b. when evaluations are done during design to check that a product continues to meet users' needs, they are known as formative evaluations
- formative evaluations cover a broad range of design processes, from the development of early sketches and prototypes through to tweaking and perfecting an almost finished design
c. evaluations that are done to assess the success of a finished product are known as summative evaluations.
- if the product is being upgraded, then the evaluation may not focus on establishing a set of requirements, but may evaluate the existing product to ascertain what needs improving
- features are then added, which can result in new usability prpblems
d. many agencies such as the National Institute of Standards and Technology (NIST) in the USA, the international standards organisations (ISO) and the British Standards Institute (BSI) set standards by which particular types of products, such as aircraft navigation systems and consumer products that have safety implications for users, have to be evaluated
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