Evaluation Techniques For Interactive Systems

What is the evaluation?

Actually, the role of evaluation is to assess our designs and test our systems to ensure that they actually behave as we expect and meet user requirements. Evaluation should not be thought of as a single phase in the design process. Ideally, evaluation should occur throughout the design life cycle, with the results of the evaluation feeding back into modifications to the design.

Goals of Evaluation.

1. To assess the extent and accessibility of the system’s functionality — the design of the system should enable users to perform their intended tasks more easily.
2. To assess users’ experience of the interaction — how easy the system is to learn, its usability and the user’s satisfaction with it.
3. To identify any specific problems with the system — These may be aspects of the design which, when used in their intended context, cause unexpected results, or confusion amongst users.

Evaluation through expert analysis

This Evaluation should occur throughout the design process. Usually, the later in the design process that an error is discovered, the more costly. In expert-based evaluation, the designer or HCI expert assesses a design based on known standard cognitive principles or empirical results. These techniques are also referred to as expert analysis techniques.

1.Cognitive walkthrough

In this method one or more HCI experts performs a series of tasks and ask a set of questions from the user to evaluate the design and user interaction.Usually, the main focus of this method is to establish how easy a system is to learn. More specifically, the focus is on learning through exploration

2..Heuristic evaluation

This method was invented and developed by Jakob Nielsen and Rolf Molich.This is a method for structuring the critique of a system using a set of relatively simple and general heuristics.The simple idea behind this heuristic evaluation is that several evaluators independently critique a system to come up with potential usability problems.

3.Model-based evaluation

This evaluation method is using a model of how a human would use a proposed system to obtain predicted usability measures by calculation or simulation.Those predictions can replace or supplement empirical measurements obtained by user testing. There are some model used this evaluations such that GOMS model, Keystroke-level model, Design rationale, Dialog models.

Evaluation through user participation

User participation in evaluation tends to occur in the later stages of development when there is at least a working prototype of the system in place. These include empirical or experimental methods, observational methods, query techniques, and methods that use physiological monitoring, such as eye-tracking and measures of heart rate and skin conductance.

Styles of evaluation

There are two types of evaluation namely laboratory studies and field studies.

Laboratory Study: In this type of evaluation studies, users are taken out of their normal work environment to take part in controlled tests, often in a specialist usability laboratory

Field Study: This type of evaluation takes the designer or evaluator out into the user’s work environment in order to observe the system in action.

Empirical methods: experimental evaluation

This method provides empirical evidence to support a particular claim or hypothesis. The evaluator who evaluate should chooses a hypothesis to test. Any changes in the behavioral measures are attributed to the different conditions.There are some factors that are important and dependent to reliability of experiement. Such that participants, variables, hypothesis and experiment design.

Observational techniques

The most common and powerful way to gather information about the actual use of a system is to observe users interacting with it. Users are asked to complete a set of predetermined tasks. The evaluator watches and records the users’ actions. It is more effective when the observations are gathering at their own place while they are doing their normal duties. There are several kind of techinique such that Think Aloud, Cooperative Evaluation, Protocol Analysis and etc..

Query techniques

This technique relies on asking the user about the interface directly.Query techniques can be useful in eliciting detail of the user’s view of a systemThere are two type of approches for this techniques...

1. Interviews: Analyst person questions user on one to one basis with prepared questions about his experience with the design and get ideas.

2. Questionnaries: Users are given a set of fixed questions about what they prefer and what they think about the design and analyst person get idea from it.

Evaluation through monitoring physiological responses

Due to the reason of increasing the interest of the ways of monitoring physiological aspects of computer systems use.This method will allow evalution experts to not only to see more clearly exactly what users do when they interact with system, but also to measure how the user feel it. They can measure it using some techniques such that eye tracking and other physiological measurement tectiques.