Interaction Design Evaluation
In the case of Interaction designing, The Evaluation is integral to the design process. It involves collecting and analyzing data about users' or potential users' experiences. The evaluation focuses on both the usability of the system as well as users’ experiences when interacting with it. There are many different evaluation methods and Which to use depends on the goals of the evaluation.
Heuristic Evaluation
In heuristic evaluation, researchers, guided by a set of usability principles known as heuristics and evaluate whether user-interface elements, such as dialog boxes, menus, navigation structure, online help, and so on, conform to tried-and-tested principles. Heuristic evaluation was developed by Jakob Nielsen and his colleagues and later modified by other researchers for evaluating the web and other types of systems.
These heuristics closely resemble high-level design principles such as making designs consistent, reducing memory load, and using terms that users understand. Jakob Nielsen’s heuristics are probably the most-used usability heuristics for user interface design.
- Visibility of system status
The system should always keep users informed about what is going on, through appropriate feedback within a reasonable time. - Match between system and the real world
The system should speak the user’s language, with words, phrases, and concepts familiar to the user, rather than system-oriented terms. - User control and freedom
Users often choose system functions by mistake and will need a clearly marked “emergency exit” to leave the unwanted state without having to go through an extended dialogue. Support undo and redo. - Consistency and standards
Users should not have to wonder whether different words, situations, or actions mean the same thing. - Error prevention
Even better than good error messages is a careful design that prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action. - Recognition rather than recall
Minimize the user’s memory load by making objects, actions, and options visible. Instructions for use of the system should be visible or easily retrievable whenever appropriate. - Flexibility and efficiency of use
Accelerators — unseen by the novice user — may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions. - Aesthetic and minimalist design
Dialogues should not contain information that is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility. - Help users recognize, diagnose, and recover from errors:
Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution. - Help and documentation:
Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user’s task, list concrete steps to be carried out, and not be too large.
Using these heuristics, Designers and researchers evaluate aspects of the interface. Those doing the heuristic evaluation go through the interface several times, inspecting the various interactive elements and comparing them with the list of usability heuristics. During each iteration, usability problems will be identified and ways of fixing them may be suggested.
Walk-Throughs
Walk-throughs offer an alternative approach to heuristic evaluation for predicting user problems without doing user testing. The meaning of walk-throughs involves walking through a task with the product and noting problematic usability features. There are main two walk-through methods called Cognitive walk-throughs and Pluralistic walk-throughs.
Cognitive Walk-Throughs
Cognitive walk-throughs involve simulating how users go about problem-solving at each step in human-computer interaction. A cognitive walkthrough starts with a task analysis that specifies the sequence of steps or actions required by a user to accomplish a task, and the system responses to those actions. The designers and developers of the software then walk through the steps as a group, asking themselves a set of questions at each step. Data is gathered during the walkthrough, and afterward, a report of potential issues is compiled. Finally, the software is redesigned to address the issues identified.
The main steps involved in cognitive walk-throughs are as follows.
- The characteristics of typical users are identified and documented, and sample tasks have been developed that focus on the aspects of the design to be evaluated.
- A designer and one or more UX researchers come together to do the analysis
- The UX researchers walk through the action sequences for each task, placing them within the context of a typical scenario.
- As the walk-through is being done, a record of critical information is compiled.
- The design is then revised to fix the problems presented. Before making the fix, insights derived from the walk-through are often checked by testing them with real users.
When doing a cognitive walk-through, it is important to document the process, keeping account of what works and what doesn’t.
Pluralistic Walk-Throughs
Pluralistic walk-throughs are another type of well-established walk-through in which users, developers, and usability researchers work together to step through a task scenario. In a pluralistic walk-through, each person is asked to assume the role of a typical user. The benefits of pluralistic walk-throughs include a strong focus on users’ tasks at a detailed level, that is, looking at the steps taken.
Compared with heuristic evaluation, walk-throughs focus more closely on identifying specific user problems at a detailed level.
Web Analytics
Web analytics is a form of interaction logging that was specifically created to analyze users’ activity on websites so that designers could modify their designs to attract and retain customers. Using web analytics, web designers and developers can trace the activity of the users who visit their website. They can see how many people came to the site, how many stayed and for how long, and which pages they visited. They can also find out about where the users came from and much more. Web analytics is therefore a powerful evaluation tool for web designers that can be used on its own or in conjunction with other types of evaluations, particularly user testing.
Web analytics are also used in evaluating non-transactional products such as information and entertainment websites, including hobbies, music, games, blogs, and personal websites and for learning. There are two types of web analytics called on-site analytics and off-site analytics.
On-site analytics are used by website owners to measure visitor behavior. Off-site analytics measure a website’s visibility and potential to acquire an audience on the Internet regardless of who owns the website. In recent years, however, the difference between off-site and on-site analytics has blurred but some people still use these terms. Additional sources may also be used to augment the data collected about a website, such as an email, direct mail campaign data, sales, and history data. The most popular web analytic tool is Google analytics. It was the most widely used on-site web analytics and statistics service.
In addition to Google Analytics, other tools continue to emerge that provide additional layers of information, good access control options, and raw and real-time data collection. For instance, Moz Analytics, TruSocialMetrics, KISSmetrics, ClickTale.
A/B Testing
Another way to evaluate a website, part of a website, an application, or an app running on a mobile device is by carrying out a large-scale experiment to evaluate how two groups of users perform using two different designs — one of which acts as the control and the other as the experimental condition, that is, the new design being tested. This approach is known as A/B testing.
A/B testing involves a “between subjects” experimental design in which two similar groups of participants are randomly selected from a single large user population.
In order to do A/B testing, a variable of interest is identified, such as the design of an advertisement.Group A is served design A, the existing design, and group B is served design B, thenew design. A dependent measure is then identified, such as how many times participants ineach group, A and B, click the advertisement that they are presented over a particular periodof time, such as a day, week, or a month. Because this is a controlled experiment, the resultscan be analyzed statistically to establish the probability that if a difference is observed, it isbecause of the treatment (in this case, the design) and not because of chance
A/B testing provides a valuable data-driven approach for evaluating the impact of small or large differences in the designs of web and social mediasites. From front-end user-interface changes to backend algorithms, from search engines to retailers ,social networking services, travel service and many startups.
Powerful though A/B testing may be, researchers are advised to check their plans in detail to ensure that they are testing what they expect to test.
Predictive Models
Like inspection methods and analytics, predictive models can be used to evaluate a product without users being present.Predictive modeling provides estimates of the efficiency of different systems for various kinds of tasks.
One kind of predictive model that has been influential in HCI and interaction design over the years is Fitts’ law. Fitts’ law predicts the time it takes to reach a target using a pointingdevice. It was originally used in human factors research to model the relationship between speed and accuracy when moving toward a target on a display.
One of its main benefits is that it can help designers decide where to locate physical or digital buttons, what size to make them, and how close together to put them on a touch display or a physical device.It has also been used for designing the layout of digital displays for input on touchscreen interfaces.
Fitts’ law states that,
where,
T = time to move the pointer to a target
D = distance between the pointer and the target
S = size of the target
k is a constant of approximately 200 ms/bit.
Fitts’ law can be useful for evaluating systems where the time to locate an object physicallyis critical to the task at hand. In particular, it can help designers think about whereto locate objects on the screen in relation to each other. This is especially useful for mobiledevices, where there is limited space for placing icons and buttons on the screen.Fitts’ law also predicts that the targets accessed most quickly on any computer display are positioned at the four corners of the screen.
References:
Helen Sharp, Jenny Preece, Yvonne Rogers — Interaction Design_ Beyond Human-Computer Interaction-Wiley (2019)
