The user interface, in the industrial design field of human–computer interaction, is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine from the human end, whilst the machine feeds back information that aids the operators' decision-making process. Examples of this broad concept of user interfaces include the interactive aspects of computer operating systems, hand tools, heavy machinery operator controls, process controls; the design considerations applicable when creating user interfaces are related to or involve such disciplines as ergonomics and psychology. The goal of user interface design is to produce a user interface which makes it easy and enjoyable to operate a machine in the way which produces the desired result; this means that the operator needs to provide minimal input to achieve the desired output, that the machine minimizes undesired outputs to the human. User interfaces are composed of one or more layers including a human-machine interface interfaces machines with physical input hardware such a keyboards, game pads and output hardware such as computer monitors and printers.
A device that implements a HMI is called a human interface device. Other terms for human-machine interfaces are man–machine interface and when the machine in question is a computer human–computer interface. Additional UI layers may interact with one or more human sense, including: tactile UI, visual UI, auditory UI, olfactory UI, equilibrial UI, gustatory UI. Composite user interfaces are UIs that interact with two or more senses; the most common CUI is a graphical user interface, composed of a tactile UI and a visual UI capable of displaying graphics. When sound is added to a GUI it becomes a multimedia user interface. There are three broad categories of CUI: standard and augmented. Standard composite user interfaces use standard human interface devices like keyboards and computer monitors; when the CUI blocks out the real world to create a virtual reality, the CUI is virtual and uses a virtual reality interface. When the CUI does not block out the real world and creates augmented reality, the CUI is augmented and uses an augmented reality interface.
When a UI interacts with all human senses, it is called a qualia interface, named after the theory of qualia. CUI may be classified by how many senses they interact with as either an X-sense virtual reality interface or X-sense augmented reality interface, where X is the number of senses interfaced with. For example, a Smell-O-Vision is a 3-sense Standard CUI with visual display and smells; the user interface or human–machine interface is the part of the machine that handles the human–machine interaction. Membrane switches, rubber keypads and touchscreens are examples of the physical part of the Human Machine Interface which we can see and touch. In complex systems, the human–machine interface is computerized; the term human–computer interface refers to this kind of system. In the context of computing, the term extends as well to the software dedicated to control the physical elements used for human-computer interaction; the engineering of the human–machine interfaces is enhanced by considering ergonomics.
The corresponding disciplines are human factors engineering and usability engineering, part of systems engineering. Tools used for incorporating human factors in the interface design are developed based on knowledge of computer science, such as computer graphics, operating systems, programming languages. Nowadays, we use the expression graphical user interface for human–machine interface on computers, as nearly all of them are now using graphics. There is a difference between a user interface and an operator interface or a human–machine interface; the term "user interface" is used in the context of computer systems and electronic devices Where a network of equipment or computers are interlinked through an MES -or Host to display information. A human-machine interface is local to one machine or piece of equipment, is the interface method between the human and the equipment/machine. An operator interface is the interface method by which multiple equipment that are linked by a host control system is accessed or controlled.
The system may expose several user interfaces to serve different kinds of users. For example, a computerized library database might provide two user interfaces, one for library patrons and the other for library personnel; the user interface of a mechanical system, a vehicle or an industrial installation is sometimes referred to as the human–machine interface. HMI is a modification of the original term MMI. In practice, the abbreviation MMI is still used although some may claim that MMI stands for something different now. Another abbreviation is HCI, but is more used for human–computer interaction. Other terms used are operator interface terminal; however it is abbreviated, the terms refer to the'layer' that separates a human, operating a machine from the machine itself. Without a clean and usable interface, humans would not be able to
A/B testing is a randomized experiment with two variants, A and B. It includes application of statistical hypothesis testing or "two-sample hypothesis testing" as used in the field of statistics. A/B testing is a way to compare two versions of a single variable by testing a subject's response to variant A against variant B, determining which of the two variants is more effective; as the name implies, two versions are compared, which are identical except for one variation that might affect a user's behavior. Version A might be the used version, while version B is modified in some respect. For instance, on an e-commerce website the purchase funnel is a good candidate for A/B testing, as marginal improvements in drop-off rates can represent a significant gain in sales. Significant improvements can sometimes be seen through testing elements like copy text, layouts and colors, but not always. Multivariate testing or multinomial testing is similar to A/B testing, but may test more than two versions at the same time or use more controls.
Simple A/B tests are not valid for observational, quasi-experimental or other non-experimental situations, as is common with survey data, offline data, other, more complex phenomena. A/B testing has been marketed by some as a change in philosophy and business strategy in certain niches, though the approach is identical to a between-subjects design, used in a variety of research traditions. A/B testing as a philosophy of web development brings the field into line with a broader movement toward evidence-based practice; the benefits of A/B testing are considered to be that it can be performed continuously on anything since most marketing automation software now comes with the ability to run A/B tests on an ongoing basis. "Two-sample hypothesis tests" are appropriate for comparing the two samples where the samples are divided by the two control cases in the experiment. Z-tests are appropriate for comparing means under stringent conditions regarding normality and a known standard deviation. Student's t-tests are appropriate for comparing means under relaxed conditions.
Welch's t test assumes the least and is therefore the most used test in a two-sample hypothesis test where the mean of a metric is to be optimized. While the mean of the variable to be optimized is the most common choice of estimator, others are used. For a comparison of two binomial distributions such as a click-through rate one would use Fisher's exact test. Like most fields, setting a date for the advent of a new method is difficult because of the continuous evolution of a topic. Where the difference could be defined is when the switch was made from using any assumed information from the populations to a test performed on the samples alone; this work was done in 1908 by William Sealy Gosset when he altered the Z-test to create Student's t-test. Google engineers ran their first A/B test in the year 2000 in an attempt to determine what the optimum number of results to display on its search engine results page would be; the first test was unsuccessful due to glitches. A/B testing research would be more advanced, but the foundation and underlying principles remain the same, in 2011, 11 years after Google’s first test, Google ran over 7,000 different A/B tests.
A company with a customer database of 2,000 people decides to create an email campaign with a discount code in order to generate sales through its website. It creates two versions of the email with different call to action and identifying promotional code. To 1,000 people it sends the email with the call to action stating, "Offer ends this Saturday! Use code A1", to another 1,000 people it sends the email with the call to action stating, "Offer ends soon! Use code B1". All other elements of the emails' copy and layout are identical; the company monitors which campaign has the higher success rate by analyzing the use of the promotional codes. The email using the code A1 has a 5% response rate, the email using the code B1 has a 3% response rate; the company therefore determines that in this instance, the first Call To Action is more effective and will use it in future sales. A more nuanced approach would involve applying statistical testing to determine if the differences in response rates between A1 and B1 were statistically significant.
In the example above, the purpose of the test is to determine, the more effective way to encourage customers to make a purchase. If, the aim of the test had been to see which email would generate the higher click-rate – that is, the number of people who click onto the website after receiving the email – the results might have been different. For example though more of the customers receiving the code B1 accessed the website, because the Call To Action didn't state the end-date of the promotion many of them may feel no urgency to make an immediate purchase. If the purpose of the test had been to see which email would bring more traffic to the website the email containing code B1 might well have been more successful. An A/B test should have a defined outcome, measurable such as number of sales made, click-rate conversion, or number of people signing up/registering. A/B tests most apply the same variant with equ
Ethnography is the systematic study of people and cultures. It is designed to explore cultural phenomena where the researcher observes society from the point of view of the subject of the study. An ethnography is a means to represent graphically and in writing the culture of a group; the word can thus be said to have a double meaning, which depends on whether it is used as a count noun or uncountable. The resulting field study or a case report reflects the knowledge and the system of meanings in the lives of a cultural group; as a method of data collection, ethnography entails examining the behaviour of the participants in a certain specific social situation and understanding their interpretation of such behaviour. Dewan further elaborates that this behaviour may be shaped by the constraints the participants feel because of the situations they are in or by the society in which they belong. Ethnography, as the presentation of empirical data on human societies and cultures, was pioneered in the biological and cultural branches of anthropology, but it has become popular in the social sciences in general—sociology, communication studies, history—wherever people study ethnic groups, compositions, social welfare characteristics, spirituality, a people's ethnogenesis.
The typical ethnography is a holistic study and so includes a brief history, an analysis of the terrain, the climate, the habitat. In all cases, it should be reflexive, make a substantial contribution toward the understanding of the social life of humans, have an aesthetic impact on the reader, express a credible reality. An ethnography records all observed behavior and describes all symbol-meaning relations, using concepts that avoid causal explanations. Traditionally, ethnography was focussed on the western gaze towards the far'exotic' east, but now researchers are undertaking ethnography in their own social environment. According to Dewan if we are the other, the ‘another’ or the ‘native’, we are still ‘another’ because there are many facades of ourselves that connect us to people and other facades that highlight our differences; the word'ethnography' is derived from the Greek ἔθνος, meaning "a company a people, nation" and -graphy, meaning "writing". Ethnographic studies focus on large cultural groups of people.
Ethnography is a set of qualitative methods that are used in social sciences that focus on the observation of social practices and interactions. Its aim is to observe a situation without imposing any deductive structure or framework upon it and to view everything as strange or unique; the field of anthropology originated from Europe and England designed in late 19th century. It spread its roots to the United States at the beginning of the 20th century; some of the main contributors like E. B. Tylor from Britain and Lewis H. Morgan, an American scientist were considered as founders of cultural and social dimensions. Franz Boas, Bronislaw Malinowski, Ruth Benedict, Margaret Mead, were a group of researchers from the United States who contributed the idea of cultural relativism to the literature. Boas's approach focused on the use of documents and informants, whereas Malinowski stated that a researcher should be engrossed with the work for long periods in the field and do a participant observation by living with the informant and experiencing their way of life.
He gives the viewpoint of the native and this became the origin of field work and field methods. Since Malinowski was firm with his approach he applied it and traveled to Trobriand Islands which are located off the eastern coast of New Guinea, he was interested in learning the language of the islanders and stayed there for a long time doing his field work. The field of ethnography became popular in the late 19th century, as many social scientists gained an interest in studying modern society. Again, in the latter part of the 19th century, the field of anthropology became a good support for scientific formation. Though the field was flourishing, it had a lot of threats to encounter. Postcolonialism, the research climate shifted towards feminism. Therefore, the field of anthropology moved into a discipline of social science. Gerhard Friedrich Müller developed the concept of ethnography as a separate discipline whilst participating in the Second Kamchatka Expedition as a professor of history and geography.
Whilst involved in the expedition, he differentiated Völker-Beschreibung as a distinct area of study. This became known as "ethnography," following the introduction of the Greek neologism ethnographia by Johann Friedrich Schöpperlin and the German variant by A. F. Thilo in 1767. August Ludwig von Schlözer and Christoph Wilhelm Jacob Gatterer of the University of Göttingen introduced the term into the academic discourse in an attempt to reform the contemporary understanding of world history. Herodotus, known as the Father of History, had significant works on the cultures of various peoples beyond the Hellenic realm such as the Scythians, which earned him the title "philobarbarian", may be said to have produced the first works of ethnography. There are different forms of ethnography: confessional ethnography. Two popular forms of ethnography are realist critical ethnography. Realist ethnography is a traditional approach used by cultural anthropologists. Characterized by Van Maanen, it reflects a particular instance taken by the researcher toward the individual being studied.
It's an objective study of the situation
Usability is the ease of use and learnability of a human-made object such as a tool or device. In software engineering, usability is the degree to which a software can be used by specified consumers to achieve quantified objectives with effectiveness and satisfaction in a quantified context of use; the object of use can be a software application, book, machine, vehicle, or anything a human interacts with. A usability study may be conducted as a primary job function by a usability analyst or as a secondary job function by designers, technical writers, marketing personnel, others, it is used in consumer electronics and knowledge transfer objects and mechanical objects such as a door handle or a hammer. Usability includes methods of measuring usability, such as needs analysis and the study of the principles behind an object's perceived efficiency or elegance. In human-computer interaction and computer science, usability studies the elegance and clarity with which the interaction with a computer program or a web site is designed.
Usability considers user satisfaction and utility as quality components, aims to improve user experience through iterative design. The primary notion of usability is that an object designed with a generalized users' psychology and physiology in mind is, for example: More efficient to use—takes less time to accomplish a particular task Easier to learn—operation can be learned by observing the object More satisfying to useComplex computer systems find their way into everyday life, at the same time the market is saturated with competing brands; this has made usability more popular and recognized in recent years, as companies see the benefits of researching and developing their products with user-oriented methods instead of technology-oriented methods. By understanding and researching the interaction between product and user, the usability expert can provide insight, unattainable by traditional company-oriented market research. For example, after observing and interviewing users, the usability expert may identify needed functionality or design flaws that were not anticipated.
A method called contextual inquiry does this in the occurring context of the users own environment. In the user-centered design paradigm, the product is designed with its intended users in mind at all times. In the user-driven or participatory design paradigm, some of the users become actual or de facto members of the design team; the term user friendly is used as a synonym for usable, though it may refer to accessibility. Usability describes the quality of user experience across websites, software and environments. There is no consensus about the relation of the terms usability; some think of usability as the software specialization of the larger topic of ergonomics. Others view these topics as tangential, with ergonomics focusing on physiological matters and usability focusing on psychological matters. Usability is important in website development. According to Jakob Nielsen, "Studies of user behavior on the Web find a low tolerance for difficult designs or slow sites. People don't want to wait.
And they don't want to learn. There's a manual for a Web site. People have to be able to grasp the functioning of the site after scanning the home page—for a few seconds at most." Otherwise, most casual users leave the site and browse or shop elsewhere. ISO defines usability as "The extent to which a product can be used by specified users to achieve specified goals with effectiveness and satisfaction in a specified context of use." The word "usability" refers to methods for improving ease-of-use during the design process. Usability consultant Jakob Nielsen and computer science professor Ben Shneiderman have written about a framework of system acceptability, where usability is a part of "usefulness" and is composed of: Learnability: How easy is it for users to accomplish basic tasks the first time they encounter the design? Efficiency: Once users have learned the design, how can they perform tasks? Memorability: When users return to the design after a period of not using it, how can they re-establish proficiency?
Errors: How many errors do users make, how severe are these errors, how can they recover from the errors? Satisfaction: How pleasant is it to use the design? Usability is associated with the functionalities of the product, in addition to being a characteristic of the user interface. For example, in the context of mainstream consumer products, an automobile lacking a reverse gear could be considered unusable according to the former view, lacking in utility according to the latter view; when evaluating user interfaces for usability, the definition can be as simple as "the perception of a target user of the effectiveness and efficiency of the Interface". Each component may be measured subjectively against criteria, e.g. Principles of User Interface Design, to provide a metric expressed as a percentage, it is important to distinguish between usability engineering. Usability testing is the measurement of ease of use of a piece of software. In contrast, usability engineering is the research and design process that ensures a product with good usability.
Usability is a non-functional requirement. As
Human factors and ergonomics
Human factors and ergonomics is the application of psychological and physiological principles to the design of products and systems. The goal of human factors is to reduce human error, increase productivity, enhance safety and comfort with a specific focus on the interaction between the human and the thing of interest, it is not changes or amendments to the work enviornment but encompases theory, methods and principles all applied in the field of ergonomics. The field is a combination of numerous disciplines, such as psychology, engineering, industrial design, anthropometry, interaction design, visual design, user experience, user interface design. In research, human factors employs the scientific method to study human behavior so that the resultant data may be applied to the four primary goals. In essence, it is the study of designing equipment and processes that fit the human body and its cognitive abilities; the two terms "human factors" and "ergonomics" are synonymous. The International Ergonomics Association defines ergonomics or human factors as follows: Ergonomics is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, the profession that applies theory, principles and methods to design to optimize human well-being and overall system performance.
Human factors is employed to fulfill the goals of occupational safety and productivity. It is relevant in the design of such things as safe furniture and easy-to-use interfaces to machines and equipment. Proper ergonomic design is necessary to prevent repetitive strain injuries and other musculoskeletal disorders, which can develop over time and can lead to long-term disability. Human factors and ergonomics is concerned with the "fit" between the user and environment or "fitting a person to a job", it accounts for the user's capabilities and limitations in seeking to ensure that tasks, functions and the environment suit that user. To assess the fit between a person and the used technology, human factors specialists or ergonomists consider the job being done and the demands on the user. Ergonomics draws on many disciplines in its study of humans and their environments, including anthropometry, mechanical engineering, industrial engineering, industrial design, information design, physiology, cognitive psychology and organizational psychology, space psychology.
The term ergonomics first entered the modern lexicon when Polish scientist Wojciech Jastrzębowski used the word in his 1857 article Rys ergonomji czyli nauki o pracy, opartej na prawdach poczerpniętych z Nauki Przyrody. The French scholar Jean-Gustave Courcelle-Seneuil without knowledge of Jastrzębowski's article, used the word with a different meaning in 1858; the introduction of the term to the English lexicon is attributed to British psychologist Hywel Murrell, at the 1949 meeting at the UK's Admiralty, which led to the foundation of The Ergonomics Society. He used it to encompass the studies in which he had been engaged during and after World War II; the expression human factors is a predominantly North American term, adopted to emphasize the application of the same methods to non-work-related situations. A "human factor" is a physical or cognitive property of an individual or social behavior specific to humans that may influence the functioning of technological systems; the terms "human factors" and "ergonomics" are synonymous.
Ergonomics comprise three main fields of research: physical and organizational ergonomics. There are many specializations within these broad categories. Specializations in the field of physical ergonomics may include visual ergonomics. Specializations within the field of cognitive ergonomics may include usability, human–computer interaction, user experience engineering; some specializations may cut across these domains: Environmental ergonomics is concerned with human interaction with the environment as characterized by climate, pressure, light. The emerging field of human factors in highway safety uses human factor principles to understand the actions and capabilities of road users – car and truck drivers, cyclists, etc. – and use this knowledge to design roads and streets to reduce traffic collisions. Driver error is listed as a contributing factor in 44% of fatal collisions in the United States, so a topic of particular interest is how road users gather and process information about the road and its environment, how to assist them to make the appropriate decision.
New terms are being generated all the time. For instance, "user trial engineer" may refer to a human factors professional who specializes in user trials. Although the names change, human factors professionals apply an understanding of human factors to the design of equipment and working methods to improve comfort, health and productivity. According to the International Ergonomics Association, within the discipline of ergonomics there exist domains of specialization. Physical ergonomics is concerned with human anatomy, some of the anthropometric and bio mechanical characteristics as they relate to physical activity. Physical ergonomic principles have been used in the design of both consumer and indu
Eye tracking is the process of measuring either the point of gaze or the motion of an eye relative to the head. An eye tracker is a device for measuring eye movement. Eye trackers are used in research on the visual system, in psychology, in psycholinguistics, marketing, as an input device for human-computer interaction, in product design. There are a number of methods for measuring eye movement; the most popular variant uses video images from. Other methods are based on the electrooculogram. In the 1800s, studies of eye movement were made using direct observations. In 1879 in Paris, Louis Émile Javal observed that reading does not involve a smooth sweeping of the eyes along the text, as assumed, but a series of short stops and quick saccades; this observation raised important questions about reading, questions which were explored during the 1900s: On which words do the eyes stop? For how long? When do they regress to seen words? Edmund Huey built an early eye tracker; the lens was connected to an aluminum pointer.
Huey studied and quantified regressions, he showed that some words in a sentence are not fixated. The first non-intrusive eye-trackers were built by Guy Thomas Buswell in Chicago, using beams of light that were reflected on the eye and recording them on film. Buswell made systematic studies into picture viewing. In the 1950s, Alfred L. Yarbus did important eye tracking research and his 1967 book is quoted, he showed that the task given to a subject has a large influence on the subject's eye movement. He wrote about the relation between fixations and interest: "All the records... show conclusively that the character of the eye movement is either independent of or only slightly dependent on the material of the picture and how it was made, provided that it is flat or nearly flat." The cyclical pattern in the examination of pictures "is dependent on not only what is shown on the picture, but the problem facing the observer and the information that he hopes to gain from the picture." "Records of eye movements show that the observer's attention is held only by certain elements of the picture....
Eye movement reflects. It is easy to determine from these records which elements attract the observer's eye, in what order, how often.""The observer's attention is drawn to elements which do not give important information but which, in his opinion, may do so. An observer will focus his attention on elements that are unusual in the particular circumstances, incomprehensible, so on.""... when changing its points of fixation, the observer's eye returns to the same elements of the picture. Additional time spent on perception is not used to examine the secondary elements, but to reexamine the most important elements." In the 1970s, eye-tracking research expanded particularly reading research. A good overview of the research in this period is given by Rayner. In 1980, Just and Carpenter formulated the influential Strong eye-mind hypothesis, that "there is no appreciable lag between what is fixated and what is processed". If this hypothesis is correct when a subject looks at a word or object, he or she thinks about it, for as long as the recorded fixation.
The hypothesis is taken for granted by researchers using eye-tracking. However, gaze-contingent techniques offer an interesting option in order to disentangle overt and covert attentions, to differentiate what is fixated and what is processed. During the 1980s, the eye-mind hypothesis was questioned in light of covert attention, the attention to something that one is not looking at, which people do. If covert attention is common during eye-tracking recordings, the resulting scan-path and fixation patterns would show not where our attention has been, but only where the eye has been looking, failing to indicate cognitive processing; the 1980s saw the birth of using eye-tracking to answer questions related to human-computer interaction. Researchers investigated how users search for commands in computer menus. Additionally, computers allowed researchers to use eye-tracking results in real time to help disabled users. More there has been growth in using eye tracking to study how users interact with different computer interfaces.
Specific questions researchers ask. The results of the eye tracking research can lead to changes in design of the interface, yet another recent area of research focuses on Web development. This can include how users react to drop-down menus or where they focus their attention on a website so the developer knows where to place an advertisement. According to Hoffman, current consensus is that visual attention is always ahead of the eye, but as soon as attention moves to a new position, the eyes will want to follow. We still cannot infer specific cognitive processes directly from a fixation on a particular object in a scene. For instance, a fixation on a face in a picture may indicate recognition, dislike, puzzlement etc. Therefore, eye tracking is coupled with other methodologies, such as introspective verbal protocols. Eye-trackers measure rotations of the eye in one of several ways, but princip
A prototype is an early sample, model, or release of a product built to test a concept or process or to act as a thing to be replicated or learned from. It is a term used in a variety of contexts, including semantics, design and software programming. A prototype is used to evaluate a new design to enhance precision by system analysts and users. Prototyping serves to provide specifications for a real, working system rather than a theoretical one. In some design workflow models, creating a prototype is the step between the formalization and the evaluation of an idea; the word prototype derives from the Greek πρωτότυπον prototypon, "primitive form", neutral of πρωτότυπος prototypos, "original, primitive", from πρῶτος protos, "first" and τύπος typos, "impression". Prototypes explore different aspects of an intended design: A Proof-of-Principle Prototype serves to verify some key functional aspects of the intended design, but does not have all the functionality of the final product. A Working Prototype represents all or nearly all of the functionality of the final product.
A Visual Prototype represents the size and appearance, but not the functionality, of the intended design. A Form Study Prototype is a preliminary type of visual prototype in which the geometric features of a design are emphasized, with less concern for color, texture, or other aspects of the final appearance. A User Experience Prototype represents enough of the appearance and function of the product that it can be used for user research. A Functional Prototype captures both function and appearance of the intended design, though it may be created with different techniques and different scale from final design. A Paper Prototype is a printed or hand-drawn representation of the user interface of a software product; such prototypes are used for early testing of a software design, can be part of a software walkthrough to confirm design decisions before more costly levels of design effort are expended. In general, the creation of prototypes will differ from creation of the final product in some fundamental ways: Material: The materials that will be used in a final product may be expensive or difficult to fabricate, so prototypes may be made from different materials than the final product.
In some cases, the final production materials may still be undergoing development themselves and not yet available for use in a prototype. Process: Mass-production processes are unsuitable for making a small number of parts, so prototypes may be made using different fabrication processes than the final product. For example, a final product that will be made by plastic injection molding will require expensive custom tooling, so a prototype for this product may be fabricated by machining or stereolithography instead. Differences in fabrication process may lead to differences in the appearance of the prototype as compared to the final product. Verification: The final product may be subject to a number of quality assurance tests to verify conformance with drawings or specifications; these tests may involve custom inspection fixtures, statistical sampling methods, other techniques appropriate for ongoing production of a large quantity of the final product. Prototypes are made with much closer individual inspection and the assumption that some adjustment or rework will be part of the fabrication process.
Prototypes may be exempted from some requirements that will apply to the final product. Engineers and prototype specialists attempt to minimize the impact of these differences on the intended role for the prototype. For example, if a visual prototype is not able to use the same materials as the final product, they will attempt to substitute materials with properties that simulate the intended final materials. Engineers and prototyping specialists seek to understand the limitations of prototypes to simulate the characteristics of their intended design, it is important to realize that by their definition, prototypes will represent some compromise from the final production design. Due to differences in materials and design fidelity, it is possible that a prototype may fail to perform acceptably whereas the production design may have been sound. A counter-intuitive idea is that prototypes may perform acceptably whereas the production design may be flawed since prototyping materials and processes may outperform their production counterparts.
In general, it can be expected that individual prototype costs will be greater than the final production costs due to inefficiencies in materials and processes. Prototypes are used to revise the design for the purposes of reducing costs through optimization and refinement, it is possible to use prototype testing to reduce the risk that a design may not perform as intended, however prototypes cannot eliminate all risk. There are pragmatic and practical limitations to the ability of a prototype to match the intended final performance of the product and some allowances and engineering judgement are required before moving forward with a production design. Building the full design is expensive and can be time-consuming when repeated several times—building the full design, figuring out what the problems are and how to solve them building another full design; as an alternative, rapid prototyping or rapid application development techniques are used for the initial prototypes, which implement part, but not all, of the complete design.
This allows designers and manufacturers to and inexpensively test the parts of the design that are most to have problems, solve those problems, build the full design. This counter-intuitive idea—that the quickest way to build something is, f