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Click depth
Click depth refers to the number of times a user has to click their mouse to get to a particular piece of content. The idea of "depth" comes from the idea of "traversing" or "climbing down" a website taxonomy.
A click depth of 4 would mean that a user has to click four separate times to retrieve a particular piece of content.
Cluster analysis
- Synonyms and see also - critical incident analysis
Cluster analysis is an advanced statistical computing technique. It is in actual fact a label for a set of related algorithms and methods for grouping objects of a similar kind into categories.
The measures of similarity vary. Most commonly, the measure of similarity being illustrated - and therefore used by the clustering algorithm - is Euclidean distance.
Cognitive walkthrough
- Synonyms and see also - cognitive jog; cognitive sprint
The Cognitive Walkthrough is an approach to evaluating an interface based upon a group of stakeholders breaking down and analysing the tasks and actions that a user must perform in order to use the system to achieve a particular goal.
The Cognitive Walkthrough method is rooted in the notion that users typically prefer to learn a system by using it to accomplish tasks rather than by, for example, studying a manual.
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 "walkthrough" the steps as a group, asking themselves a set of questions at each step. Data is gathered during the walkthrough, and afterwards a report of potential issues is compiled. Finally the software is redesigned to address the issues identified.
The Cognitive Walkthrough method is used to identify usability issues in an interaction application, focusing on how easy it is for new users to accomplish tasks with the system.
In the context of a production methodology, cognitive walkthroughs can be conducted during Definition - on wireframes, process flows, and paper and interactive prototypes - and during Implementation to validate early beta release candidates.
Colour blindness
Any time you use colour to convey information in the interface, you should also use clear, secondary cues to convey the information to those who won't be experiencing any colour coding today.
Most people have colour displays nowadays, but they are not universal. In addition, approximately 10% of human males, along with a rare sprinkling of females, have some form of colour blindness.
The cones in the eye are the source of colour vision. We have cones separately sensitive to red, green, and blue. If the red ones are not functioning that is called protanopia. If the green are not functioning, that is called deuteranopia. Absence of blue, extremely rare, is called tritanopia.
Protanopia and deuteranopia are the most popular forms of colour blindness, collectively called red/green blindness. (There are, in fact, significant differences in their effects, but those differences have no real effect on interaction design.) While tritanopia is far more rare, it nonetheless rules out dependence on yellow-blue differentiation without secondary cues.
Secondary cues can consist of anything from the subtlety of grey scale differentiation to having a different graphic or different text label associated with each colour presented.
Conceptual models
- Synonyms and see also - mental models
A conceptual model is a representation of how, in a general sense, something "works".
User experience guru Don Norman defined three types of models that occur when creating an interactive application:
- Conceptual models - how the designer or IA would like the user to think and believe the application works
- Mental models - how the user actually thinks the application works
- Implementation models - how the application works from a technical point of view
In practise, it's hard to tease apart conceptual and mental models. A conceptual model can be described in lots of ways. It can have a written description or explanation, and is often a graphic, although it can also be a chart, a written paragraph or a flowchart.
The key is that the conceptual model - irrespective of how it is actually represented - expresses an explanation of the system's behaviour (to both the designer and the user) that is easy and intuitive. Importantly, it does not have to be how the system actually works.
Consistency
The following principles, taken together, offer the interaction designer tremendous latitude in the evolution of a product without seriously disrupting those areas of consistency most important to the user.
Levels of consistency - the importance of maintaining strict consistency varies. The following list is ordered from those interface elements demanding the most faithful consistency effort to those demanding the least. Paradoxically, many people assume that the order of items one through five should be exactly the reverse, leading to applications that look alike, but act completely different in unpredictable ways:
- Interpretation of user behaviour, e.g., shortcut keys maintain their meanings
- Invisible structures
- Small visible structures
- The overall "look" of a single application or service--splash screens, design elements
- A suite of products
- In-house consistency
- Platform-consistency
"Invisible structures" refers to such invisible objects as Microsoft Word's clever little right border that has all kinds of magical properties, if you ever discover it is there. It may or may not appear in your version of Word. And if it doesn't, you'll never know for sure that it isn't really there, on account of it's being invisible.
Which is exactly what is wrong with invisible objects and why is consistency so important?
Other objects are, strictly speaking, visible, but do not appear to be controls, so users, left to their own devices, might never discover their manipulability. The secret, if you absolutely insist on one, should be crisp and clean, for example: "You can click and drag the edges of current Macintosh windows to size them", not: "You can click and drag various things sometimes, but not other things other times."
"Small visible structures" refers to icons, size boxes, scroll arrows, etc. The appearance of such objects needs to be strictly controlled if people are not to spend half their time trying to figure out how to scroll or how to print. Location is only just slightly less important than appearance. Where it makes sense to standardize location, do so.
Inconsistency - it is just as important to be visually inconsistent when things must act differently as it is to be visually consistent when things must act the same. Avoid uniformity. Make objects consistent with their behaviour. Make objects that act differently look different.
The most important consistency is consistency with user expectations. The only way to ascertain user expectations is to do user testing. No amount of study and debate will substitute.
Content analysis
- Synonyms and see also - textual analysis
Content analysis is the study of recorded human communications, such as books, web sites, paintings and laws. It's a technique for making inferences by objectively and systematically identifying specified characteristics of messages.
For any piece of communication, content analysis essentially seeks to answer the following core questions: "Who says what, to whom, why, to what extent and with what effect?"
Context of use analysis
- Synonyms and see also - context analysis; usability context analysis
The context of use is the actual conditions under which a given product, system or service is used, or will be used in a normal day-to-day working situation.
It is important to carry out usability tests, prototyping sessions, meetings, user studies and other "user-dependent" activity in the relevant context of use to get as high an ecological validity of your findings as possible.
A context of use analysis is a questionnaire-based evaluation of all aspects of the actual conditions under which a given product, system or service is used, or will be used in a normal day-to-day working situation.
Contextual inquiry
- Synonyms and see also - ethnography; data capture; requirements capture
Contextual inquiry is essentially ethnography by a different name.
In other words, it is a form of (method of doing) anthropology (in commercial and professional situations). It's a data capture technique popularised by Karen Holtzblatt in her book Contextual Design.
At the heart of the technique is the notion of in-situ observation, where the researcher simply watches and observes a user going about their normal daily activity. The researcher is free to ask questions if they don't understand something - and the user is encouraged to provide a commentary of their activities if they feel happy to do so - but the primary focus is simply on observation.
Critical incident analysis
Critical incident (CI) analysis is an open-ended retrospective evaluation technique for finding out what users feel are the critical features of a product, system or service being evaluated.
In this kind of analysis, users (familiar with the product, system or service) are asked to identify specific incidents which they experienced personally and which had an important effect on the final outcome. The emphasis is on incidents rather than vague opinions.
The technique focuses on user behaviour, so it can be used in situations where video recording is not practicable so long as the inherent bias of retrospective judgement is understood.
CI analysis uses Content Analysis in order to summarise the experiences of many users or many experiences of the same user.
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