asynchronous groupware [1] software used to help people to work in groups, but not requiring those people to be working together at the same time. (asynchronous = not coordinating at a single point in time). Examples include: electronic mail the routing of forms through an office ("workflow") collaborative hypertext systems (such as the web) file-sharing systems that allow different people to edit the same file at different times version-control systems, often used in software engineering to coordinate changes made by multiple programmers to the same program document annotation, such as the markup used for editing and proofreading collaborative writing systems see also: {email} {hypertext} {synchronous groupware} {website design} categories: algorithm animation [10] algorithms are the formal procedures for performing some computational task, such as the procedure to sort a set of numbers. An algorithm animation is a graphical display of process over time (auditory cues are also quite common). Algorithm animations are especially useful for teaching and explaining complex processes and for helping programmers to debug their programs. This illustration shows one frame of an animation of the Quicksort algorithm. see alsoinformation visualization categories: EBS [100] electronic brainstorming; the use of computers to support idea generation, especially in a collaborative setting. Computer support can be helpful by simplifying the collection and organization of ideas, by providing anonymity and thus supporting more fluid generation of ideas, and by providing support for analyzing, evaluating, and prioritizing ideas after they have been generated. see also: {groupware} categories: environmental profile [1002] a characterization of the environment in which a system will be used. Aspects may include ambient lighting and noise, temperature, humidity, smoke, chemical substances, vibrations, the visual environment, enclosures and furnishings, the user terminal, and other human activity. see also: {contextual inquiry} {user profile} categories: polymorphic artifact [1003] a software artifact (application, widget, dialogue) that can adapt its appearance and behavior to suit different users, uses, and technologies (e.g. I/O devices). The adaptation may be at the level of functionality, process of use, or appearance. see also: {user profile} categories: dwell time [1004] the time a user lingers at a certain step of a task, such as the time that a user holds the pointer over a button, or the time spent viewing an individual web page. categories: 2-second rule [1005] a loose principle that a user should not need to wait more than 2 seconds for certain types of system response, such as application-switching and application launch time. The choice of 2 seconds is somewhat arbitrary, but a reasonable order of magnitude. categories: ruggedized device [1006] a piece of hardware designed for abuse, such as adverse environments and usage. For instance, ruggedization might be useful in industrial settings, outdoor work, sports, emergency uses, or rough handling by children. Ruggedizing may include techniques such as rubber components, shock absorption material, break-resistant (concave) screens, water-resistant construction, and sturdy mounting. see also: {clinical workstation} {stress testing} categories: pilot test [1007] or formative test; an initial run of a study (e.g. an experiment, survey, or interview) for the purpose of verifying that the test itself is well-formulated. For instance, a colleague or friend can be asked to participate in a user test to check whether the test script is clear, the tasks are not too simple or too hard, and that the data collected can be meaningfully analyzed. categories: in-car interfaces [1008] applications designed for use in a car, such as radios, mobile phones, and GPS systems. Some interface design factors include safety, visual display (if any), rapid use, low cognitive overhead, and hands-free use. see also: {auditory I/O} {safety} categories: simulator sickness [1009] virtual environment sickness or cybersickness; an adverse reaction to immersion in a 3D virtual environment characterized by symptoms of nausea, motion sickness, disorientation, and loss of control over movement. This reaction is typically explained by sensory conflict theory, the idea that the body reacts when visual and vestibular signals provide conflicting information about the body's orientation. Vestibular senses are orientation information from the inner ear. see also: {immersive interfaces} {VR} categories: <3D Graphics> <3D Graphics> distributed cognition [101] the notion of people thinking and solving problems collectively, rather than simply as isolated individuals. Those interested in distributed cognition are interested in how people communicate and jointly use artifacts to accomplish joint work. see also: {cognitive psychology} {role} categories: MouseKeys [1010] a feature that allows the pointer position to be controlled with keyboard keys instead of the mouse, intended especially for people with motor disabilities who have difficulty using a mouse. categories: locked-in syndrome [1011] a level of paralysis where people can make no voluntary movements other than direction of eye gaze, despite their consciousness and awareness. Communication channels are thus extremely limited, and a brain-computer interface is one possible computer interface that can work. see also: {brain-computer interface} {mobility impairment} {motor impairment} categories: white finger [1012] or dead finger; loss of bloodflow in the hand due to prolonged exposure to vibration (as when operating machinery), which can cause numbness, increase sensitivity to cold, and lead to necrosis (dead tissue). categories: brain-computer interface [1013] or brain-body interface; an interface directly controlled by brain waves as opposed to physical movement. Current state-of-the-art can only distinguish a few brain states, so such interfaces usually are led by yes-no decisions. These interfaces require training and are currently designed for users with "locked-in syndrome", who have paralysis so severe that a brain interface is one of their only means of communication. see also: {locked-in syndrome} categories: glare [1014] light that interferes with viewing a display, especially light reflected from the surface of the display. Glare can be reduced in several ways: the display can be positioned to avoid glare, generally by placing it perpendicular to other light sources. the screen can be coated with a material that diffuses light, thus reducing glare. a glare hood can reduce external light hitting the screen. |Top Level I/O Devices Output Devices luminance ratio [1015] for displays, the ratio of the brightness of ambient light to screen brightness, which affects the legibility of the display. see also: {CRT} {glare} {legibility} categories: context-sensitive help [1016] helpful information available within a task that is specific to the current activity of the user, as opposed to being general in nature. see also: {embedded help} categories: convenience [1017] the level of effort and discomfort required to successfully use an interface in accomplishing a task. see also: {error} categories: efficiency [1018] the rate or speed at which an interface enables a user to accurately and successfully complete a task. see also: {convenience} {error} categories: effectiveness [1019] the degree to which an interface facilitates a user in accomplishing the task for which it was intended. see also: {convenience} {efficiency} {usefulness} categories: usability lab [102] a lab designed for user testing, typically a quiet room with computer equipment and a space for an observer to sit, along with a special observation area (possibly behind a one-way mirror) and equipment for videotaping. Computers in a usability lab are also often set up with logging software to capture user keystrokes and mouse movements and with scan converters, used to videotape computer screens. see also: {user testing} categories: vibratory feedback [1020] feedback a user gets from a physical device that can vibrate, such as a pager indicating an incoming message or a joystick vibrating when a user pushes its value outside a safe operating range. see also: {haptic interface} {white finger} categories: latching [1021] the capability of a control to be set in a specific position (or state) and to remain in that position; the opposite of a spring-loaded mode. see also: {spring-loaded mode} categories: control selectivity [1022] the degree to which a control can be manipulated without accidentally activating other controls. A common problem is to position buttons or keys too closely, leading to the wrong button being pressed. see also: {Fitts' Law} categories: dwell [1023] the property of a control that keeps it from activating until it has been 'held' (or manipulated) for a certain period of time, thus preventing accidental activation from being briefly hit unintentionally. see also: {dwell time} {hysteresis} categories: control sensitivity [1024] the ease with which a control can be activated or set to a certain level. Less sensitive devices require greater effort. see also: {control selectivity} {dwell} categories: fail-safe [1025] a property of a device or system that inherently prevents certain failure modes or errors. An example is the inability to start your car when it isn't in 'park'. see also: {safety} {safety-critical system} categories: proxemics [1026] issues dealing with spatial relationships between interface components, devices, and users. For instance, the distance between users can determine what communication device is used and what settings are functional (such as volume). Also, the position of devices with respect to the user can affect their accessibility & efficiency. see also: {ergonomics} categories: forcing function [1027] an aspect of a design that prevents a user from taking an action without explicitly performing another action. For example, writing on a PDA won't have any effect unless you first turn it on, preventing data corruption from accidentally bumping it. see also: {fail-safe} categories: cosmesis [1028] the effect that the appearance of a device has on the perception of the person who is using it; it's "fashion statement". The degree to which the user can feel attractive and socially acceptable in using the device. categories: sensory defensiveness [1029] and tactile defensiveness; an adverse reaction that some users may have to touching devices with certain temperatures, textures, or materials, which may be due to allergies, physical sensitivities, or psychological aversion. categories: think aloud protocol [103] a technique in user testing where users are asked to speak their thoughts as they perform a task. While the focus in user testing is primarily on how effectively a user performs the required tasks (and not on how users believe they are performing), verbalizations are quite useful in understanding mistakes that are made and getting ideas for what the causes might be and how the interface could be improved to avoid those problems. see also: {question-asking protocol} {user testing} categories: syntax-directed editor [1030] a text editor, used primarily for writing software, that automatically formats the program code for readability based on its knowledge of the structure (the syntax) of the program. It may also simplify entering information by enabling the programmer to quickly jump between related parts of the program or select keywords from lists without having to remember them. see also: {IDE} {RAD} categories: Common User Access [1032] CUA; a set of user interface standards established for IBM platforms in 1987. see also: {Apple Macintosh} {Microsoft Windows} {Motif} {Open Look Graphical User Interface} categories: AWT [1033] Abstract Windows Toolkit; a Java library for development of user interfaces, including standard widgets and layout tools. see also: {Java} {layout manager} {widget} categories: low vision [1035] limitations of eyesight short of complete blindness. Low vision may include myopia, blurred vision, limited visual angle, spotted vision, darkened eyesight, fractured images, and blindspots. Approaches to helping this situation include using large fonts and imagery, using screen magnification tools, and using high-contrast or allowing the user to adjust colors and contrast. see also: {screen-enlargement utility} categories: language disorder [1036] any of a variety of common cognitive impairments (that limit the production and understanding of language), such as dyslexia, and speech impairments. Many of these impairments can be assisted by reducing the linguistic complexity of the interface (which also helps international users, i.e. non-native speakers), increasing the legibility and readability of text, and removing the need for speech input and output. see also: {cognitive impairment} {hearing impairment} {legibility} {readability} {speech impairment} categories: mobility impairment [1037] physical limitations affecting walking and transportation. These impairments can be a factor when designing public terminals and kiosks, such as ATM machines, which can be inconvenient for wheelchair access. Technology can also be designed to assist with mobility problems by providing mobile access. see also: {human factors} {motor impairment} categories: hearing impairment [1038] difficulty hearing or deafness. For those who are hard of hearing, volume controls can help them use a computer, as well as output devices that enable them to plug in headphones and control the position and direction of speakers. For deafness or partial deafness, provide an option to turn off sound in the interface and use alternative ways of displaying information, such as closed captions, and providing visual alerts instead of or in addition to audio alerts. Many of these solutions for users with hearing impairments are quite useful to unimpaired users who work in noisy environments or wish to work without having audio disturb others around them. see also: {closed captions} {redundant modalities} categories: situational impairment [1039] a difficulty accessing computers due to the context or situation one is in, as opposed to a physical impairment. Examples include noise, poor lighting, distractions, other tasks that require use of hands or eyes, and social constraints such as the inappropriateness of using devices with audio when attending a lecture. For instance, users who are driving are unable to effectively work with complex visual displays. Users in noisy situations (or quiet ones) may be unable to use audio or speech interfaces. see also: {disability} {in-car interfaces} categories: multimedia [104] multimedia is typically used to refer to the use of any dynamic media: audio, video, or animation. When used in this sense, there are numerous issues in how people deal with motion, timing, change, and ephemerality. Strictly speaking, multimedia refers to the use of more than one medium at a time (including for instance, text and graphics, and possibly other sensory modalities such as touch and smell). From this perspective, the question is how people integrate two media - how do they map onto each other and what are the strengths of each, so various media can be applied at the most appropriate times. categories: visual impairment [1040] low vision, color blindness, or blindness. Low-vision users need the ability to scale fonts and images and need optimal contrast and legibility. Blind users need to access computers through non-visual modalities, such as screen readers or Braille output devices. see also: {color blindness} {haptic interface} {low vision} {screen reader} {tactile interface} categories: spiral model [1041] a classic approach to project management. The spiral model is an iterative approach that begins by developing basic requirements, building small simple prototypes, evaluating those prototypes, and then expanding into refined requirements and consecutively larger prototypes, until a complete deliverable product is created. Prior to the final product, each prototype is deliberately built with the expectation that it will be thrown away. see also: {design-prototype-test cycle} {iterative design} {pervasive usability} {waterfall model} categories: task completion time [1042] a measure of the time it takes a user to perform a task (from start to finish). This is a typical metric in usability evaluation. categories: mental map [1043] (website navigation) a representation in a person's mind of the structure of a website, which is likely to be incomplete and simplified. A mental map helps people simplify the job of remembering what they've seen to the problem of remembering an overall structure rather than every page and link. When a mental map is a fairly accurate representation of the actual site structure, a person can use it to quickly navigate without a lot of mental effort. However, where the mental map doesn't match the actual site structure, navigation can be slower than optimal and people can make incorrect inferences about what is and is not included on the site. see also: {information architecture} {navigation} {scope notes} categories: VDU [1044] visual display unit; a screen or monitor. Also, VDT, visual display terminal. see also: {CRT} {flat screen display} {raster display} {vector display} categories: open card sort [1045] a type of card sort that asks users to suggest | that topics group into. Users are provided with a list of topics (e.g. content pieces to go on a website) and are asked to group them and to label the groups with category labels. If the set of topics is large enough, they are asked to further group the groups or further subdivide the groups, labeling all the groupings. These groupings are then combined to determine a user-based conceptualization of the site structure, and the labels given are used as a starting point for labeling the site navigation. see also: {card sorting} {closed card sort} {information architecture} {similarity matching} categories: closed card sort [1046] a type of card sort that asks users to sort topics into pre-defined |, as opposed to asking the users to label the |. Users are provided with a list of topics (e.g. content pieces to go on a website) and are asked to sort them into pre-existing | (such as for adding topics to a currently existing site with a pre-existing structure). Combining suggestions from multiple users helps identify the optimal categorization of topics. see also: {card sorting} {information architecture} {open card sort} {similarity matching} categories: similarity matching [1047] a technique for identify conceptual |. Users are given a set of topics, and they are asked to rate the similarity of pairs of topics (on some scale, e.g. 1 to 10). These ratings can them be combined with a statistical technique called cluster analysis to identify groupings of topics that most closely match user ratings. However, the technique doesn't identify the label or "meaning" of those groups, so the person doing the analysis must interpret the groups and suggest labels if they are needed (or go back to users and ask for candidate labels). This technique can be used, for instance, to discover possible organizations of content for a website. It has the advantage over card sort techniques that the data from each user is somewhat richer (and therefore more informative), but it is generally more time consuming than card sorts. see also: {card sorting} {closed card sort} {multi-dimensional scaling} {open card sort} categories: early adopter [1048] a person who chooses to purchase or use relatively new technology before it is fully embraced by the mass market. Early adopters are therefore people who have a stronger need for the technology (such as a specific application that doesn't apply broadly), a lower reluctance to use it (such as techno-geeks), or the ability to overcome barriers to adopting it (such as cost or a difficult user interface). see also: {critical mass} {domain expert} {user acceptance testing} categories: ISO 9241 [1049] "Ergonomics requirements for office work with visual display terminals (VDTs)"; a set of international standards for using computers, including hardware, visual display, and interaction guidelines, developed by the International Standards Organization (ISO). see also: {standard} categories: wizard of oz prototype [105] a prototype that only works by having someone behind-the-scenes who is pulling the levers and flipping the switches. The wizard of oz technique in user testing has a user interacting with an interface without knowing that the responses are being generated by a human, not a computer. This allows testing of some difficult interface concepts before a system is fully working. For example, in a search system, a user may type in a query, and an expert behind the scenes rewrites the query in a formal syntax or hand-selects search results. This allows you to test theories in query formulation and filtering of results. Similarly, the wizard of oz technique is popular in testing natural language interfaces where, for instance, the choice of what syntax to support in the system is driven by what syntax users actually use during the tests. see also: {chauffeured prototype} {prototyping theatre} {user testing} categories: ISO 9000 [1050] 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 on those measurements, and focus on continual improvement. ISO 9000 is about usability because it is centered on the fundamental principle of customer focus, i.e. understanding customer needs, involving customers, and exceeding customer expectations. see also: {ISO 9241} {quality assurance} {quality inspection} categories: customization [1051] the ability for a user to set the characteristics of a system to suit their preferences and needs. In desktop software, this is typically done with a "Preferences..." option. Customization may be related to superficial characteristics, such as the skin for an MP3 player or the desktop image, or may be critical functionality of the system. see also: {favorites list} {individualization} {personalization} {theme} categories: personalization [1052] modifying an application with personally-relevant information for an individual user, such as providing their name, email address, or favorite color. see also: {adaptive interfaces} {customization} {individualization} categories: individualization [1053] modifying a system to suit the needs and preferences of a single individual user. see also: {adaptive interfaces} {customization} {diversity} {personalization} categories: persona [1054] a description of a specific person who is a target user of a system being designed, providing demographic information, needs, preferences, biographical information, and a photo or illustration. Typically, multiple personas are developed in the early stages of design that represent the spectrum of the target audience. Personas are one piece of a "scenario", the other piece being a description of how this person would typically interact with the system being designed. The point of developing personas is to avoid the trap of designing for the "average" user that doesn't actually exist, and instead to make sure that the system will work for somebody specific rather than no one in particular. see also: {demographics} {environmental profile} {scenario} {target audience} {target configuration} {user profile} categories: site visit [1055] going to target users' workplace to see how they work, interact directly with them, conduct interviews, and see their work artifacts. Interaction can range from directly interviewing to inconspicuously observing. Visits can be brief or long-term. see also: {artifact analysis} {day-in-the-life studies} {ethnography} {job shadowing} {observational study} categories: psychophysics [1056] a discipline of psychology that measures the response characteristics of human perception in a method parallel to measuring the response characteristics of physical materials. The prototypical examples are human perception of the intensity of light and sound. People report the intensity of sound as increasing linearly when the actual physical power is increasing exponentially. This is the basis of the logarithmic decibel scale. see also: {ergonomics} {human factors} categories: time [1057] a typical measurement in usability studies, and a typical metric for target system performance, including for instance: response time, learning time, and task completion time. see also: {delay} {dwell time} {Fitts' Law} {Hick's Law} {power law of practice} {speed} {task completion time} categories: speed [1058] a metric for human performance. How quickly does a person react to a stimulus (reaction time)? How much time does it take for someone to perform a given task (task completion time)? Also, a metric for system performance. How quickly does a system respond to user input (responsiveness)? How quickly can it process a given algorithm? How does its speed relate to the number of users or the amount of data to process (scalability)? see also: {benchmarks} {event-driven interface} {responsiveness} {task completion time} {time} categories: tethered viewpoint [1059] a virtual reality or immersive environment where people's actions control a remote representation of themselves, an avatar, or a device, that they can watch and control within the environment, as opposed to thinking of themselves as directly inside the environment. For instance, motion detectors can allow someone to control a puppet or character within a video environment as they watch. see also: {avatar} {egocentric viewpoint} {exocentric viewpoint} {immersive interfaces} {VR} categories: <3D Graphics> <3D Graphics> luddite [106] a person who is anti-technology, even violently so; a person who is a critic of the overuse, misuse, or abuse of technology. The term is derived from the name of Ned Ludd, an 18th century riot leader who led workers in smashing industrial equipment to oppose unemployment caused by industrialization. see also: {automation} categories: exocentric viewpoint [1060] a virtual reality or immersive environment that is displayed around a person, for instance, by projecting scenes onto adjacent walls, rather than displaying it directly to someone's senses (e.g. with a head-mounted display). see also: {egocentric viewpoint} {head-mounted display} {immersive interfaces} {tethered viewpoint} {VR} categories: <3D Graphics> <3D Graphics> egocentric viewpoint [1061] a virtual reality or immersive environment that is displayed into a person, by projecting it directly to a person's senses with, for instance, a head-mounted display and headphones, as opposed to displaying the environment onto screens external to the person. see also: {binocular display} {exocentric viewpoint} {head-mounted display} {immersive interfaces} {tethered viewpoint} {VR} categories: <3D Graphics> <3D Graphics> tabletop display [1062] a display built into a tabletop. This may be advantageous in helping people to view it from many positions, including sitting and standing, in an environment where they need to be moving around frequently, in enabling multiple people to view the display simultaneously, and to make surface space available that would otherwise be needed for monitors. categories: single-display groupware [1063] SDG; a system where 2 or more people can simultaneously interact with a computer displaying on a single monitor. This is quite common for arcade games, but may be practical for certain educational applications and monitoring applications. The key problem in collaborative applications is preventing users from interfering with or distracting each other. see also: {face-to-face} {shared whiteboard} {synchronous groupware} categories: unistroke text input [1064] pen-based input of alphanumeric characters based on an alphabet of gestures that can all be written with a single pen stroke. For instance, uppercase H usually requires at least 3 strokes (two vertical bars and a crossbar), while lowercase h can be easily written with 1 continuous stroke. A unistroke alphabet simplifies the automatic recognition of letters and can speed up writing (with practice). see also: {gesture} {stroke recognition} categories: pinyin input [1065] Chinese-character input based on the pinyin alphabet. Pinyin is a method of writing Chinese in a roman alphabet. With pinyin input systems, users can type the Chinese words phonetically, and then select among a few alternative Chinese characters that represent alternative words with the given pronunciation. Similar phonetic input systems are also used for entering Japanese. see also: {internationalization} {Unicode} categories: term rotation [1066] in an index (such as for finding information on a website), listing multi-word terms under each significant word in the term. Thus, "information architecture" would also be listed under "architecture, information" and "graphical user interface" would also appear under "user interface, graphical", so that a person can find the listing based on any word they may consider looking up. see also: {controlled vocabulary system} {information architecture} {lexicon} {thesaurus} categories: satisficing [1067] a theory of human reasoning that says that people minimize cognitive load by minimizing reasoning and using quick heuristics to make decisions. Thus, people avoid complex memory, planning, and decision-making in favor of acting upon information immediately available perceptually, well-known information, and pretty good rules of thumb. categories: information foraging [1068] a theory of people's information-consumption behavior, where people are viewed as foraging for information like animals foraging for food. People tend to stay in one place (e.g. on one website) and exhaust the supply of information before moving on. This satisfies a cost/risk tradeoff because moving on to another location may not provide additional useful information. People also refine their goals based on what they find, so you can't treat information-seeking as having a steady target. As a result of these considerations, information should be designed to help people determine if they’ve exhausted the supply of information (e.g. by clearly indicating the scope of a website) and should provide opportunities for serendipitous discovery. categories: website topology [1069] the structure of connections between pages on a website. Typical structures include: hierarchy / tree - the most traditional is to organize a site into | and sub|. linear sequence - used for sequential stories or processes. matrix / grid - 2-dimensional grid, useful for 2-dimensional maps or for information spaces that vary along 2 dimensions (e.g. products available by size and color). full mesh - a site with every page linked to every other page, which is only really possible for small sites. arbitrary web - a set of links with no planned or explicit structure. hybrid - a combination of the above, which is how any practical, real-world site is actually structured. see also: {information architecture} {navigation} {sitemap} categories: color blindness [107] an inability to distinguish certain color combinations. About 8% of males and 0.5% of females are colorblind in some fashion, so it is common enough to be a highly-significant factor in design. Red-green color blindness is most common, followed by yellow-blue color blindness. To avoid problems for users with color blindness, make sure that color is never the sole way of distinguishing objects. Never expect users to be able to name colors or recognize a color by name. Use differences in brightness to make colored regions distinct, and test your interfaces in grayscale to confirm that they are still usable. see also: {low vision} categories: WYSIWYN [1070] What You See is What You Need; a variation of WYSIWYG, advocating that the information that a user needs is actually immediately visually perceptual. categories: ecological validity [1071] the extent to which the context of a user study matches the context of actual use of a system, such that it is reasonable to suppose that the results of the study are representative of actual usage and that the differences in context are unlikely to impact the conclusions drawn. All factors of how the study are constructed must be considered: how representative are the tasks, the users, the context, and the computer systems? see also: {context of use} {day-in-the-life studies} {ethnography} {external validity} {job shadowing} {site visit} {usability lab} categories: diagnostic evaluation [1072] a usability evaluation specifically designed to diagnose the problems with a system in order to fix them, as opposed to a measurement study that merely attempts to rate or rank a system without identifying how to make an improvement. see also: {comparative study} {criterion testing} {diagnostic pretesting} categories: context of use [1073] the situational factors that influence the use and usability of a system, including environmental factors (physical conditions such as space, time, temperature, noise), organizational factors (social network, management and organizational pressures, and work processes), and technical/system factors (network connectivity, system configuration, system stability), and broad social factors (cosmesis, family conflicts, career aspirations, economy, ethical standards). see also: {BPR} {cosmesis} {environmental profile} categories: conversion rate [1074] the percentage of people who achieve a given task from a given starting point. On websites, the percentage of people starting at page A who get to page B. So for instance, if 1000 come to a homepage on a given day, and 600 of them click a link to a subpage, then you would say the site "has a 60% conversion rate of staying on the site after the homepage". Similarly, if 1000 people come to the homepage and 100 of those people bought a product, you'd say that "10% of site visitors were converted to buyers". Conversion rate is a common web metric to evaluate the performance of a site. categories: cognitive load [1075] the level of effort associated with thinking and reasoning (including perception, memory, language, etc.), thus potentially interfering with other thought processes. A user interface strives to minimize the cognitive load associated with operating the interface itself so that all of a person's cognitive resources are available for their task. see also: {cognitive psychology} categories: synthetic metric [1076] a value which is the result of combining other metrics, which are measurements of properties of designs, systems, or user performance. An example is to average the results of several subjective ratings scores that come from users responding to an interface, i.e. if we asked users to rate on a scale of 1 (bad) to 10 (good) the attractiveness, interest, and ease of an interface, we could average these 3 scores and treat the average as an estimate of their overall subjective reaction (which may or may not be a useful metric). categories: descriptive metric [1077] a value that describes some aspect of a system. For instance, if we were trying to automatically evaluate a web page, we might want to rate its "text legibility" based on a measure of the font size used. An automated tool could identify the modal font size used on the page (a descriptive metric) and report this value. The metric identifies modal font sizes for different websites but makes no specific claim as to what the implications of that value are. This is in contrast to a predictive metric. see also: {automatic evaluation} {predictive metric} {synthetic metric} categories: predictive metric [1078] a value describing some aspect of a system that purports to provide a prediction or estimate of the usability of the system. For instance, if we described the font size used on a web page as a predictive metric (e.g. claiming that larger sizes are more legible, at least up to a point), then a designer would suppose that because increasing the font size improves their "score", that doing so will also increase the usability of the design. This is in contrast to a descriptive metric, which makes no explicit claim as to the implications of the measurement. see also: {automatic evaluation} {descriptive metric} categories: separable user interface [1079] a user interface implementation that allows the user interface to be modified without modifying the backend code, and vice versa. see also: {front end} {model-view-controller} categories: group-enabling technologies [108] systems that add group support to single-user applications, by providing, for instance, telepointers, overlays for collaborative annotations, shared windows, chat facilities, and methods for finding and connecting to other users. see also: {session control} {shared whiteboard} {telepointer} categories: stereopsis [1080] the perception of depth based on the differences in images that reach the 2 eyes. see also: {binocular display} {chromostereopsis} {depth perception} {head-mounted display} categories: <3D Graphics> <3D Graphics> touch interactive display [1082] TID; an input device that overlays a screen, or touchscreen, that recognizes where the user touches as input. see also: {touchscreen} categories: redundant coding [1083] or secondary coding; representing information in more than one way so that users have more than one opportunity to perceive and understand it, to reinforce the information, to make the information more accessible (because one representation may not work for a certain technology or user), or to suit user preferences. A common example on websites it provide redundant text links in addition to a graphic navigation bar. Another example on websites is that links are both blue and underlined, so that a color-impaired user could see the underlines, and a user who chose to turn underlining off could still see the color. see also: {redundant modalities} categories: vigilance task [1084] a type of task where a user must maintain attention on the task while waiting for an uncommon, unpredictable event, such as monitoring security cameras or a radar display. see also: {critical incident analysis} {locus of attention} categories: attitude measure [1085] a quantitative value representing the subjective rating or opinion of users reacting to seeing or using a system, as opposed to performance measures like task completion time or number of errors. see also: {benchmarks} {performance measure} {task completion time} {usability metrics} categories: performance measure [1086] a quantitative rating on how someone performed a task, such as the time it took to complete, the number of errors they made in doing it, their success rate, time spent in a particular phase of a process, frequency with which one option was chosen over another, or learning time. This is in contrast to an attitude measure. see also: {attitude measure} {error} {task completion time} categories: learning time [1087] the amount of time it takes to acquire a new skill or piece of knowledge up to a given level of mastery. Since nothing is ever learned perfectly, target levels of mastery must be defined, such as the ability to complete a task (ever), the ability to perform a task at a certain average completion time, or the ability to perform the task with 5 or fewer errors. A common goal is to minimize the necessary amount of time to learn how to use software, or to make the learning time essentially zero (a "walk-up-and-use" interface). see also: {automaticity} {learning curve} {power law of practice} {training} {walk-up-and-use} categories: embedded help [109] text that is integrated into the user interface and provides instructions right next to the part of the interface that it applies to. It is not a separate help system and not even something that needs to be requested by the user, but rather is simply on the screen. This is an extremely common approach for walk-up-and-use systems, displays, and systems that are infrequently used, such as kiosks, many types of websites, and many multimedia titles. see also: {concurrent help} {readability} {technical writing} categories: within-subjects design [1091] a study designed to make a comparison of 2 or more designs and that compares them by having each user try each design, measuring their performance for each design. The most common problem is that people learn over time, and so they frequently perform better on the 2nd design than the first, regardless of the relative quality of the designs. Thus, it's important to counterbalance such a study, having half the subjects start with one design and half start with the other, in order to avoid having the order effects give an advantage to one design. see also: {between-subjects design} {confound} {Hawthorne effect} {internal validity} categories: between-subjects design [1092] a study designed to make a comparison of 2 or more designs and that compares them by having one set of users try one design and another set of users try another design, measuring their performance for each design. This usually requires more users than a within-subjects design, but more easily avoids confounds introduced when a single person uses both designs. see also: {within-subjects design} categories: breakdown analysis [11] a technique for analyzing user interaction sequences which looks at times when users are focused on figuring out how to use the system (a "breakdown") versus times when users are performing their intended tasks. see also: {critical incident analysis} {stress testing} categories: gee whiz factor [110] that aspect of a design which shows off a technical skill or a sensational design that makes people say "that's neat!", but really has no useful purpose. categories: ellipsis [1101] an ellipsis ("...") is used at the end of menu items to indicate that additional information is needed before the action of the menu item is carried out, usually by bringing up a dialog box. Dialog boxes that are merely confirmation (e.g. "Save changes?") should not have an ellipsis in the corresponding menu item, only dialog boxes that let the user specify additional information. see also: {dialog box} categories: random observation [1102] a type of field study to gather usage data, where you observe users at random points throughout the day to see what they're doing with your software at those times, thus capturing real-life as opposed to laboratory usage. Random observation saves considerable time versus constant monitoring of users (as in a day-in-the-life study), but may mean you don't get an adequate idea of how a user's entire work process functions and may miss critical events. see also: {critical incident analysis} {diary study} categories: software monitor [1103] a piece of software that tracks user activity to understand the actual usage of an application or to keep track of actions during user testing. Typically, it records user events, such as keystrokes and mouse clicks, and may record higher-level actions, such as entries into form fields, menu items used, web pages visited, windows opened, etc. see also: {automatic evaluation} {hit logs} {journaled session} categories: locking [1104] in groupware and database systems, restricting access to an object that someone else is editing to prevent conflicts, such as inconsistent changes. see also: {floor control} categories: skip link [1105] a link on a web page which, when clicked, skips down to a place lower on the page (i.e. a page link). The deliberate intention of a skip link is to enable a user to skip unimportant, uninteresting, or redundant information and get down to the useful information on a page. A typical use is, when designing web pages for the blind, to put a link at the top of the page that skips over standard company logos and navigation that would be redundant on every page so that the blind user doesn't have to listen to these items on every page visited. see also: {screen reader} categories: selection bias [1106] in choosing test users for a usability study, selection bias is any imperfection in the selection process that gets either the wrong types of users (people who aren't in your target audience) or a sample of users that is not random and therefore is biased toward one type of user rather than another (e.g. even though you want to target both novice and expert users, you only manage to recruit expert users, so your results will be skewed). The most common example is a volunteer bias, since people who volunteer to be in a study may not be representative of your overall target audience; they may, for instance, have more free time, have a greater interest in technology, and be more outgoing than those who wouldn't volunteer. see also: {target audience} categories: situated action [1107] the notion that people's behavior is contextualized, i.e. the situation is a very important factor in determining what people will do. In the extreme view, this is the idea that you can't generalize and predict people's behavior from one situation to the next. Thus, this suggests an approach to usability which says to understand each user's or, more commonly, each organization's specific and detailed needs in designing software for them by carefully examining how they work and how situational and organizational factors fit into that process. see also: {ethnography} {fundamental attribution error} categories: disability [1108] a mental or physical characteristic that limits the ability for someone to function at full capacity. Disabilities are frequently categorized into: visual impairments: blindness, low vision, color blindness hearing impairments: deafness, hard of hearing motor impairments: mobility impairments, difficulty using hands, muscular dystrophy, arthritis, paralysis, some speech difficulties, repetitive stress injuries (carpal tunnel syndrome) cognitive impairments: learning disabilities, dyslexia, language comprehension and production difficulties, memory loss In user interface design, these disabilities can be planned for and designs can be created to reduce or eliminate the impact of a disability on the use of computers using, for instance, accessibility aids. Other | of disability that may be less often considered but are still relevant to interface design include seizure disorders (sensitivity to strobing stimuli), personality disorders (such as attention deficit), sensitivity to pain or other tactile sensations, and allergies (such as sensitivities to metals). see also: {assistive technology} {cognitive impairment} {hearing impairment} {motor impairment} {seizure disorder} {speech impairment} {visual impairment} categories: demand characteristics [1109] a potential problem in user studies where people being studied have a tendency to behave in a way that reacts to what they think is expected of them. In user testing, for instance, people may tend to say an interface is good or bad if they hear the tester suggest that it is good or bad. People may tend to try harder during user testing than they would in natural situations because they believe they are expected to be able to complete tasks. see also: {confound} {Hawthorne effect} {internal validity} categories: data-centered interface [111] a user interface designed to support users editing object and documents and not designed around the use of application software. Users focus on documents without worrying about which applications are being used and possibly using multiple applications on the document without realizing it. Some attempts to support this type of interaction in operating systems include OLE and OpenDoc. see also: {OOUI} categories: baseline [1112] baseline is basically where things "are" in the sense that what we see is what is being done by a "majority" within a competitive space. Now you could argue that, because most are doing something, more audiences experience the same thing. But that depends on the weight of what we find in the analysis. If we discover that most content is found under similar/the same labels, then user expectations are best served by doing the same -- but this is NOT best practice. This is simply using convention to reduce guesswork. For example, on one project we had used 'Feedback' to label where visitors should contact the client in a number of ways. When given the scenario, "You would like to complain to that their navigation sucks," every single user looked for "Contact Us." The argument went, "doesn't that stifle creativity?" Yes and no. But that convention can change quickly. Basing designs on baseline is, in my opinion, a short-term measure for meeting an immediate need. -- Ron Biggs see also: {best practices} {convention} categories: best practices [1113] the things that we do in recognition and presentation of natural workflows, hierarchies and priorities, cues, integration (physical vs. mental), etc. Labels, on the other hand, come and go -- best practices endure, for the most part, longer than labels because they're more about patterns of behavior rather than convention. While patterns may change, they don't change as quickly as convention. Vocabulary in the English language is a good example of how quickly conventions change; but "best practices" for how to communicate really haven't changed a great deal over time. Why? Because we have uncovered patterns (via cognitive psychology, etc.) that people respond to with respect to verbal communication, and we have based our practices accordingly. So, while baseline can get us a certain distance, we transcend baseline by application of best practices in ferreting out user goals and task/domain expectations. Other definitions of best practice include: A recorded description of process that is recognized by experts as an effective, efficient and/or appropriate method for accomplishing a task. Because a best practice is selected from among competing processes that can yield similar results, it is in effect documented wisdom. A method or technique that is recognized by experts as superior to alternatives in its effectiveness and efficiency. Experiences that contribute to success support but are not in themselves best practices. Methods and tools that lead to sustainable improvement in quality, productivity, time to market, and/or, communication. Processes, practices, or systems identified in public and private organizations that performed exceptionally well and are widely recognized as improving an organization’s performance and efficiency in specific areas. categories: mental integration [1114] when the user is required to remember an item from a previous page to compare it to something on the present page, just the opposite of physical integration. Better designs will make it easier for the user to compare items by having them side-by-side. see also: {cognitive load} {physical integration} categories: physical integration [1115] when items that have to be compared are side by side on the screen so people can see both things simultaneously and not have to remember something from a previous page or have to scroll up or down to find the second item. see also: {best practices} {cognitive load} {gestalt principles} {mental integration} categories: tiering [1116] a way of taking the tasks to be performed and putting them in several tiers . The most important are readily available; the less important tasks are on subsidiary levels. Designers used to put all tasks on the menu bar even if they were rarely used. With tiering, only the most important and most-often used tasks would be available without an extra click. Tiering is representative of the continuum form of organizing content. see also: {information architecture} {menubar} {task analysis} categories: balloon help [112] a help facility in Mac OS that displays a speech balloon over widgets and screen regions when the users pause over them. The speech balloon typically contains a title and a short description. Similar in some ways to tooltips, except that tooltips typically don't include descriptions and balloon help can be turned on and off. see also: {tooltip} categories: "You are here" indicator [113] a way of indicating the current location (or view area) when looking at an overview map, site map, navigation bar, etc. The indicator can be as simple as a dot, a bounding rectangle, an arrow, or a hilited item. "You are here" indicators are a critical component in helping users orient themselves in large information spaces, such as websites and other hypertext structures. They help people address the questions of "Where am I?", "How did I get here?", and "Where can I go now?" see alsonavigation categories: open captions [1136] like closed captions, open captions present text that represents the audio portion of a video, except open captions are displayed explicitly on the screen. see also: {closed captions} categories: