Glossary » Usability Methods

instructional design

the design of an educational system, focusing on how people learn and how learning can be facilitated. An instructional designer will set educational objectives for the system and design the interaction to avoid straying from those objectives. A wide variety…

inter-observer reliability

or inter-coder reliability; the degree to which 2 observers record the same data (or in some cases, draw the same conclusions) in the same circumstances. Lack of reliability in observations can indicate that observers are missing important details, that they…

interaction design

the design of how a user communicates, or interacts, with a computer. Interaction designers focus on the flow of interaction, the dialog between person and computer, how input relates to output, stimulus-response compatibility, and feedback mechanisms.

This is in contrast…

internal validity

the degree to which the design of a study allows you to accurately attribute an observation to a specific cause rather than alternative causes. An undesirable alternative cause for your result is known as a “confound”.

An example is to…

interview

gathering information about users by talking directly to them. An interview can typically gather more information than a questionnaire and go into a deeper level of detail. Interviews are good for getting subjective reactions, opinions, and insights into how people…

inverted pyramid process

An iterative process oriented around exploring a wide variety of alternatives. Rather than build a single prototype and testing, in the inverted pyramid process, you build lots of low-cost alternatives, such as thumbnails, evaluate them, then refine to the next…

ISO 9000

a set of international standards for quality management. The standards help ensure that an organization produces quality products and services and runs the organization well. The main themes are to apply a systematic process, measure performance and make decisions based…

iterative design

the idea that design should be done in repeated cycles where, in each cycle, the design is elaborated, refined, and tested, and the results of testing at each cycle feed into the design focus of the next cycle.

This is…

job shadowing

an observation technique involving following someone throughout their workday to understand all the details of their work.

journaled session

a user testing situation in which usage data, such as keystrokes and mouseclicks, are automatically recorded into logs or journals. This data can later be analyzed to determine a user’s pattern of behavior, find trouble spots, examine learning times, and…

KLM

Keystroke Level Model. A simple GOMS technique dealing mainly with observable events and organized as a single stream of sequential operators. KLM is easy to learn and can provide fast, but crude, task execution times.

lasso-tap

circling and tapping on an object with a pen — used as a selection technique in pen-based systems.

learner-centered design

designing around the specific needs of a learner; designing to foster learning. Similar to user-centered design (UCD), learner-centered design focuses on the tasks and goals of someone who is learning, motivates them, and helps them grow as they use the…

Likert scale

a type of survey question where respondents are asked to rate the level at which they agree or disagree with a given statement. For example:

I find this software easy to use.
strongly disagree 1 2 3 4 5 6

…

load testing

testing a software system to verify that it can handle high-volume use; for instance, checking that a website can handle a large number of simultaneous users, checking that a game can handle a large number of players, or confirming that…

low-fidelity prototype

a prototype that is sketchy and incomplete, that has some characteristics of the target product but is otherwise simple, usually in order to quickly produce the prototype and test broad concepts.

mental model

Humans establish mental models of how things work, or how they would behave in a particular situation. For example, having been a student at a university for a while, a student can establish a “mental model” of attending a university.…

meta-analysis

an analysis of an issue combining the results from multiple studies, especially a statistical technique for combining the statistical data from multiple experiments. The statistical method is especially useful when prior studies appear to give conflicting results or provide questionable…

metaphor

the use of one idea or object to represent another; making an implicit comparison between concepts to provide insight into those concepts.

Metaphor is used widely in graphical user interfaces to help set users’ expectations and make the behavior of…

Meyer’s Law

T = A + B * SQRT(D/W)

T = time to move to a target
D = distance to target
W = width of target
A ~ -13 msec
B ~ 108 msec

Meyer’s Law is…

MHP

Model Human Processor. A simple cognitive architecture used as the basis of the GOMS family of user modeling techniques. This representation of human cognition consists of separate components for cognitive, motor, and perceptual processors (and associated buffers), as well as…

mission creep

or scope creep; the tendency for a project to accumulate more and more required project goals as development proceeds, such as additional software features or sections of a website. Mission creep typically delays a project, runs it over budget, and…

mockup

another term for prototypes, usually referring to low-fidelity prototypes, such as paper illustrations, screenshots, or simple configurations of screens with limited interaction.

multi-dimensional scaling

MDS; a statistical technique useful for understanding the structure of a domain, especially useful in early stages of design. People are asked to rate pairs of concepts for their similarity, then these similarities are fed into the statistical algorithm to…

mundane realism

the extent to which a study, such as user testing, matches the real-world situation to which its results will be applied. This is an example of an external validity concern. This means matching the types of users being tested and…