Evaluation Techniques for Interactive Systems
Designers use lots of evaluation techniques to make more interactive software design. In this article, I’m going to write about how this evaluation process matters in the design process.
What is Evaluation
When we build a product, we need to make sure our product or design should meet the requirement. So this process of assessing the design and testing the system is called evaluation.
Usually, evaluation should occur throughout the design life cycle rather than keeping it as a single phase. Evaluating in the early stages is important because we can find out problems with our system and correct them before they cost a lot. Therefore, users are getting involved in this process.
Goals of Evaluation
The evaluation has three main goals:
to assess the extent and accessibility of the system’s functionality
to assess users’ experience of the interaction
to identify any specific problems with the system
The system’s functionality is important in that it must accord with the user’s requirements. In other words, the design of the system should enable users to perform their intended tasks more easily. This includes not only making the appropriate functionality available within the system but making it clearly reachable by the user in terms of the actions that the user needs to take to perform the task.
Evaluation through expert analysis
The first evaluation of a system should ideally be performed before any implementation work has started.it can be expensive to carry out user testing at regular intervals during the design process, and it can be difficult to get an accurate assessment of the experience of interaction from incomplete designs and prototypes. Consequently, a number of methods have been proposed to evaluate interactive systems through expert analysis. We will consider some approaches to the expert analysis below.
o Cognitive walkthrough
The cognitive walkthrough was originally proposed and later revised by Polson and colleagues as an attempt to introduce psychological theory into the informal and subjective walkthrough technique. In this, the sequence of actions refers to the steps that an interface will require a user to perform in order to accomplish some known task. The information of the walkthrough will help the designers to decide priorities for correcting the design.
o Heuristic evaluation
Heuristic evaluation, developed by Jakob Nielsen and Rolf Molich, is a method for structuring the critique of a system using a set of relatively simple and general heuristics. Heuristic evaluation can be performed on a design specification so it is useful for evaluating early design. But it can also be used on prototypes, storyboards and fully functioning systems. It is therefore a flexible, relatively cheap approach. The general idea behind heuristic evaluation is that several evaluators independently critique a system to come up with potential usability problems.
o Model-based evaluation
Certain cognitive and design models provide a means of combining design specification and evaluation into the same framework. In this approach, we can identify how people would use a created software design to obtain predicted usability measures by calculations and simulation.
Evaluation through user participation
The techniques we have considered so far concentrate on evaluating a design or system through analysis by the designer, or an expert evaluator, rather than testing with actual users. However, useful as these techniques are for filtering and refining the design, they are not a replacement for actual usability testing with the people for whom the system is intended, the users. There are some techniques that can do evaluation using users. Below I mention those techniques and styles of evaluation.
o Styles of evaluation
We get two distinct evaluation styles as:
Laboratory studies — These are performed under laboratory conditions. Users will move to a special environment.
Field studies — These are performed in the field. That means designers and reviewers go to the environment where the user is in to do the evaluation.
o Empirical methods: experimental evaluation
One of the most powerful methods of evaluating a design or an aspect of a design is to use a controlled experiment. This provides empirical evidence to support a particular claim or hypothesis. It can be used to study a wide range of different issues at different levels of the design. When a hypothesis is testing, we can use different attributes to measure it. They are participants chosen, the variables tested and manipulated, and the hypothesis tested.
o Observational techniques
This is a popular way to gather information about the actual use of a system is to observe users interacting with it. Usually, they are asked to complete a set of predetermined tasks, although, if the observation is being carried out in their place of work, they may be observed going about their normal duties. The evaluator watches and records the users’ actions. There are some techniques used to evaluate systems by observing user behavior, such as think-aloud and cooperative evaluation, protocol analysis, automatic protocol analysis tools, and post-task walkthroughs.
o Query techniques
Query techniques can be useful in eliciting detail of the user’s view of a system. They embody the philosophy that states that the best way to find out how a system meets user requirements is to ‘ask the user’. They can be used in the evaluation and more widely to collect information about user requirements and tasks. This method gets the user’s viewpoint directly and may reveal issues that have not been considered by the designer. So this is a very easy and important technique for designers.
There are two main types of query technique,
-Interviews
-Questionnaires
Evaluation through monitoring physiological responses
One of the problems with most evaluation techniques is that we are reliant on observation and the users want to tell what they are doing and how they are feeling. we were able to measure these things directly?
Potentially this will allow us not only to see more clearly exactly what users do when they interact with computers but also to measure how they feel. There are two areas that we can use to measure them.
-eye-tracking
-physiological measurement.
My Next article on another topic from human-computer interaction. It is “Universal design for interactive systems”.
