14 October 2007

Software Engineering: Patterns (Just the Quotes)

"Many fields use patterns in various ways: In music and literature, a pattern is the coherent structure or design of a song or book. In art, a pattern is the composition or plan of a work of graphic or plastic art. In architecture, a pattern is an architectural design or style. In psychology, a pattern is a thinking mechanism that is basic to the brain's operation, helping one to perceive things quickly. In archeology, a pattern is a group of phases having several distinguishing and fundamental features in common. In linguistics, a pattern is the manner in which smaller units of language are grouped into larger units [...]" (Peter Coad, "Object-Oriented Patterns", 1992)

"With each pattern, small piecework is standardized into a larger chunk or unit. Patterns become the building blocks for design and construction. Finding and applying patterns indicates progress in a field of human endeavor." (Peter Coad, "Object-Oriented Pattern", 1992)

"Design patterns are not about designs such as linked lists and hash tables that can be encoded in classes and reused as is. Nor are they complex, domain-specific designs for an entire application or subsystem. The design patterns [...] are descriptions of communicating objects and classes that are customized to solve a general design problem in a particular context." (Erich Gamma et al, "Design Patterns: Elements of Reusable Object-Oriented Software", 1994)

"Design patterns make it easier to reuse successful designs and architectures. Expressing proven techniques as design patterns makes them more accessible to developers of new systems. Design patterns help you choose design alternatives that make a system reusable and avoid alternatives that compromise reusability. Design patterns can even improve the documentation and maintenance of existing systems by furnishing an explicit specification of class and object interactions and their underlying intent. Put simply, design patterns help a designer get a design 'right' faster." (Erich Gamma et al, "Design Patterns: Elements of Reusable Object-Oriented Software", 1994)

"Design patterns should not be applied indiscriminately. Often they achieve flexibility and variability by introducing additional levels of indirection, and that can complicate a design and/or cost you some performance. A design pattern should only be applied when the flexibility it affords is actually needed." (Erich Gamma et al, "Design Patterns: Elements of Reusable Object-Oriented Software", 1994)

"The best designers will use many design patterns that dovetail and intertwine to produce a greater whole." (Erich Gamma et al, "Design Patterns: Elements of Reusable Object-Oriented Software", 1994)

"It is commonly said that a pattern, however it is written, has four essential parts: a statement of the context where the pattern is useful, the problem that the pattern addresses, the forces that play in forming a solution, and the solution that resolves those forces. [...] it supports the definition of a pattern as 'a solution to a problem in a context', a definition that [unfortunately] fixes the bounds of the pattern to a single problem-solution pair." (Martin Fowler, "Analysis Patterns: Reusable Object Models", 1997) 

"Design patterns are standard solutions to recurring problems, named to help people discuss them easily and to think about design. […] Patterns are abstract, core solutions to problems that recur in different contexts but encounter the same ‘forces’ each time." (Ian Graham & Alan O’Callaghan, "An introduction to patterns", 2003)

"Patterns today are most useful because they provide a language for designers to communicate in. Rather than having to explain a complex idea from scratch, the designer can just mention a pattern by name and everyone will know, at least roughly, what is meant. This is how designers in many other disciplines communicate their design ideas." (Ian Graham & Alan O’Callaghan, "An introduction to patterns", 2003)

"Design patterns provide the cores of ready-made solutions that can be used to solve many of software’s most common problems. Some software problems require solutions that are derived from first principles. But most problems are similar to past problems, and those can be solved using similar solutions, or patterns." (Steve C McConnell, "Code Complete: A Practical Handbook of Software Construction" 2nd Ed., 2004)

"In addition to their complexity-management benefit, design patterns can accelerate design discussions by allowing designers to think and discuss at a larger level of granularity." (Steve C McConnell, "Code Complete: A Practical Handbook of Software Construction" 2nd Ed., 2004)

"Design thinking taps into capacities we all have but that are overlooked by more conventional problem-solving practices. It is not only human-centered; it is deeply human in and of itself. Design thinking relies on our ability to be intuitive, to recognize patterns, to construct ideas that have emotional meaning as well as functionality, to express ourselves in media other than words or symbols." (Tim Brown, "Change by Design: How Design Thinking Transforms Organizations and Inspires Innovation", 2009)

"Conformity to patterns is not a measure of goodness." (Ralph Johnson)

11 October 2007

Software Engineering: Prototyping (Just the Quotes)

"The classical vertical arrangement for project management is characterized by an inherent self-sufficiency of operation. It has within its structure all the necessary specialized skills to provide complete engineering capabilities and it also has the ability to carry on its own laboratory investigations, preparation of drawings, and model or prototype manufacture. (Penton Publishing Company, Automation Vol 2, 1955)

"A mathematical model is any complete and consistent set of mathematical equations which are designed to correspond to some other entity, its prototype. The prototype may be a physical, biological, social, psychological or conceptual entity, perhaps even another mathematical model." (Rutherford Aris, "Mathematical Modelling", 1978)

"Economic principles underlie the overall structure of the software lifecycle, and its primary refinements of prototyping, incremental development, and advancemanship. The primary economic driver of the life-cycle structure is the significantly increasing cost of making a software change or fixing a software problem, as a function of the phase in which the change or fix is made." (Barry Boehm, "Software Engineering Economics", 1981)

"A problem with this 'waterfall' approach is that there will then be no user interface to test with real users until this last possible moment, since the "intermediate work products" do not explicitly separate out the user interface in a prototype with which users can interact. Experience also shows that it is not possible to involve the users in the design process by showing them abstract specifications documents, since they will not understand them nearly as well as concrete prototypes." (Jakob Nielsen, "Usability Engineering", 1993)

"One should not start full-scale implementation efforts based on early user interface designs. Instead, early usability evaluation can be based on prototypes of the final systems that can be developed much faster and much more cheaply, and which can thus be changed many times until a better understanding of the user interface design has been achieved." (Jakob Nielsen, "Usability Engineering", 1993)

"Scenarios are an especially cheap kind of prototype. […] Scenarios are the ultimate reduction of both the level of functionality and of the number of features: They can only simulate the user interface as long as a test user follows a previously planned path. […] Scenarios are the ultimate minimalist prototype in that they describe a single interaction session without any flexibility for the user. As such, they combine the limitations of both horizontal prototypes (users cannot interact with real data) and vertical prototypes (users cannot move freely through the system)." (Jakob Nielsen, "Usability Engineering", 1993)

"The entire idea behind prototyping is to cut down on the complexity of implementation by eliminating parts of the full system. Horizontal prototypes reduce the level of functionality and result in a user interface surface layer, while vertical prototypes reduce the number of features and implement the full functionality of those chosen (i.e., we get a part of the system to play with)." (Jakob Nielsen, "Usability Engineering", 1993)

"The entire idea behind prototyping is to save on the time and cost to develop something that can be tested with real users. These savings can only be achieved by somehow reducing the prototype compared with the full system: either cutting down on the number of features in the prototype or reducing the level of functionality of the features such that they seem to work but do not actually do anything." (Jakob Nielsen, "Usability Engineering", 1993)

"Although it might seem as though frittering away valuable time on sketches and models and simulations will slow work down, prototyping generates results faster." (Tim Brown, "Change by Design: How Design Thinking Transforms Organizations and Inspires Innovation", 2009)

"Just as it can accelerate the pace of a project, prototyping allows the exploration of many ideas in parallel. Early prototypes should be fast, rough, and cheap. The greater the investment in an idea, the more committed one becomes to it. Overinvestment in a refined prototype has two undesirable consequences: First, a mediocre idea may go too far toward realization - or even, in the worst case, all the way. Second, the prototyping process itself creates the opportunity to discover new and better ideas at minimal cost." (Tim Brown, "Change by Design: How Design Thinking Transforms Organizations and Inspires Innovation", 2009)

"Prototypes should command only as much time, effort, and investment as is necessary to generate useful feedback and drive an idea forward. The greater the complexity and expense, the more 'finished' it is likely to seem and the less likely its creators will be to profit from constructive feedback - or even to listen to it. The goal of prototyping is not to create a working model. It is to give form to an idea to learn about its strengths and weaknesses and to identify new directions for the next generation of more detailed, more refined prototypes. A prototype’s scope should be limited. The purpose of early prototypes might be to understand whether an idea has functional value." (Tim Brown, "Change by Design: How Design Thinking Transforms Organizations and Inspires Innovation", 2009)

"Prototyping at work is giving form to an idea, allowing us to learn from it, evaluate it against others, and improve upon it." (Tim Brown, "Change by Design: How Design Thinking Transforms Organizations and Inspires Innovation", 2009)

"Since openness to experimentation is the lifeblood of any creative organization, prototyping - the willingness to go ahead and try something by building it - is the best evidence of experimentation." (Tim Brown, "Change by Design: How Design Thinking Transforms Organizations and Inspires Innovation", 2009)

"In analytics, it’s more important for individuals to be able to formulate problems well, to prototype solutions quickly, to make reasonable assumptions in the face of ill-structured problems, to design experiments that represent good investments, and to analyze results." (Foster Provost & Tom Fawcett, "Data Science for Business", 2013)

"Because of the short timeline, it’s tempting to jump into prototyping as soon as you’ve selected your winning ideas. But if you start prototyping without a plan, you’ll get bogged down by small, unanswered questions. Pieces won’t fit together, and your prototype could fall apart." (Jake Knapp et al, "Sprint: How to Solve Big Problems and Test New Ideas in Just Five Days", 2016)

"But perhaps the biggest problem is that the longer you spend working on something - whether it’s a prototype or a real product - the more attached you’ll become, and the less likely you’ll be to take negative test results to heart. After one day, you’re receptive to feedback. After three months, you’re committed." (Jake Knapp et al, "Sprint: How to Solve Big Problems and Test New Ideas in Just Five Days", 2016)

"Sometimes you can’t fit everything in. Remember that the sprint is great for testing risky solutions that might have a huge payoff. So you’ll have to reverse the way you would normally prioritize. If a small fix is so good and low-risk that you’re already planning to build it next week, then seeing it in a prototype won’t teach you much. Skip those easy wins in favor of big, bold bets." (Jake Knapp et al, "Sprint: How to Solve Big Problems and Test New Ideas in Just Five Days", 2016)

"The prototype is meant to answer questions, so keep it focused. You don’t need a fully functional product - you just need a real-looking façade to which customers can react." (Jake Knapp et al, "Sprint: How to Solve Big Problems and Test New Ideas in Just Five Days", 2016)

"You can prototype anything. Prototypes are disposable. Build just enough to learn, but not more. The prototype must appear real." (Jake Knapp, "Sprint: How to Solve Big Problems and Test New Ideas in Just Five Days", 2016)

06 October 2007

Software Engineering: Users (Just the Quotes)

"Computers do not decrease the need for mathematical analysis, but rather greatly increase this need. They actually extend the use of analysis into the fields of computers and computation, the former area being almost unknown until recently, the latter never having been as intensively investigated as its importance warrants. Finally, it is up to the user of computational equipment to define his needs in terms of his problems, In any case, computers can never eliminate the need for problem-solving through human ingenuity and intelligence." (Richard E Bellman & Paul Brock, "On the Concepts of a Problem and Problem-Solving", American Mathematical Monthly 67, 1960)

"The most important property of a program is whether it accomplishes the intention of its user." (C Anthony R Hoare, Communications of the ACM, 1969)

"In computer design three levels can be distinguished: architecture, implementation and realisation; for the first of them, the following working definition is given: The architecture of a system can be defined as the functional appearance of the system to the user, its phenomenology. […] The inner structure of a system is not considered by the architecture: we do not need to know what makes the clock tick, to know what time it is. This inner structure, considered from a logical point of view, will be called the implementation, and its physical embodiment the realisation." (Gerrit A Blaauw, "Computer Architecture", 1972)

"There always is an architecture, whether it is defined in advance - as with modern computers - or found out after the fact - as with many older computers. For architecture is determined by behavior, not by words. Therefore, the term architecture, which rightly implies the notion of the arch, or prime structure, should not be understood as the vague overall idea. Rather, the product of the computer architecture, the principle of operations manual, should contain all detail which the user can know, and sooner or later is bound to know." (Gerrit A Blaauw, "Computer Architecture", 1972)

"Models are models of something, namely, [they are] reflections, representations of natural and artificial originals, that can themselves be models again. […] Models, in general, do not cover all the attributes of the originals they are representing, but only those [attributes] that seem relevant to the actual model creators and/or model users." (Herbert Stachowiak, "Allgemeine Modelltheorie", 1973)

"Models are not assigned per se uniquely to their originals. They perform their replacement function: a) for definite – cognitive and/or handling, model-using – subjects, b) within definite time intervals, c) under restrictions of definite operations of thought or fact. […] Models are not only models of something. They are also models for somebody, a human or an artificial model user. They perform thereby their functions in time, within a time interval. And finally, they are models for a definite purpose." (Herbert Stachowiak, "Allgemeine Modelltheorie", 1973)

"Two of the most difficult areas of data-base management are the design of an information structure and the reduction of that structure to a data structure which is compatible with and managed by the DBMS. […] Data-base management systems are tools to be applied by the users of these systems to build an accurate and useful model of their organization and its information needs. To accomplish this, the information structure must accurately define and characterize the items of data and the relations among them that are of interest to the users. This is no small task, for it demands a knowledge of the organization and the distribution of information among its various parts." (Robert W Taylor & Randall L Frank, "CODASYL Data-Base Management Systems", 1976)

"The utility of a language as a tool of thought increases with the range of topics it can treat, but decreases with the amount of vocabulary and the complexity of grammatical rules which the user must keep in mind. Economy of notation is therefore important." (Kenneth E Iverson, "Notation as a Tool of Thought", 1979)

"People’s mental models are apt to be deficient in a number of ways, perhaps including contradictory, erroneous, and unnecessary concepts. As designers, it is our duty to develop systems and instructional materials that aid users to develop more coherent, useable mental models. As teachers, it is our duty to develop conceptual models that will aid the learner to develop adequate and appropriate mental models. And as scientists who are interested in studying people’s mental models, we must develop appropriate experimental methods and discard our hopes of finding neat, elegant mental models, but instead learn to understand the messy, sloppy, incomplete, and indistinct structures that people actually have." (Donald A Norman, "Some Observations on Mental Models" [in "Mental Models"], 1983)

"A database management system is a collection of interrelated files and a set of programs that allow users to access and modify these files. A major purpose of a database system is to provide users with an abstract view of the data. That is, the system hides certain details of how the data is stored and maintained. However, in order for the system to be usable, data must be retrieved efficiently. This concern has lead to the design of complex data structures for the representation of data in the database. Since many database systems users are not computer-trained, the complexity is hidden from them through several levels of abstraction in order to simplify their interaction with the system." (Henry F. Korth & Abraham Silberschatz, "Database System Concepts" 2nd Ed., 1991)

"Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user's task, list concrete steps to be carried out, and not be too large." (Jakob Nielsen, "Usability Engineering", 1993)

"The system should always keep users informed about what is going on, through appropriate feedback within reasonable time." (Jakob Nielsen, "Usability Engineering", 1993)

"Users can work with analysts and object designers to formulate and tune system requirements. People from business, analytical and object design disciplines can come together, learn from each other and generate meaningful descriptions of systems that are to be built. Each participant and each project has slightly different concerns and needs. Practical application of use cases can go a long way to improve our ability to deliver just what the customer ordered. (Rebecca Wirfs-Brock, "Designing scenarios: Making the case for a use case framework", 1993)

"Users often do not know what is good for them. […] Users have a very hard time predicting how they will interact with potential future systems with which they have no experience. […] Furthermore, users will often have divergent opinions when asked about details of user interface design." (Jakob Nielsen, "Usability Engineering", 1993)

"Users often raise questions that the development team has not even dreamed of asking. This is especially true with respect to potential mismatches between the users' actual task and the developers' model of the task. Therefore, users should be involved in the design process through regular meetings between designers and users. Users participating in a system design process are sometimes referred to as subject matter experts, or SMEs." (Jakob Nielsen, "Usability Engineering", 1993)

"Users are not designers, so it is not reasonable to expect them to come up with design ideas from scratch. However, they are very good at reacting to concrete designs they do not like or that will not work in practice. To get full benefits from user involvement, it is necessary to present these suggested system designs in a form the users can understand." (Jakob Nielsen, "Usability Engineering", 1993)

"The next best thing to having good ideas is recognizing good ideas from your users. Sometimes the latter is better." (Eric S Raymond, "The Cathedral & the Bazaar: Musings on Linux and Open Source by an Accidental Revolutionary", 1999)

"Treating your users as co-developers is your least-hassle route to rapid code improvement and effective debugging." (Eric S Raymond, "The Cathedral & the Bazaar: Musings on Linux and Open Source by an Accidental Revolutionary", 1999)

"Ultimately, users visit your website for its content. Everything else is just the backdrop." (Jakob Nielsen, "Designing Web Usability", 1999)

"The physical design process is a key phase in the overall design process. It is too often ignored until the last minute in the vain hope that performance will be satisfactory. Without a good physical design, performance is rarely satisfactory and throwing hardware at the problem is rarely completely effective. There is no substitute for a good physical design, and the time and effort spent in the physical design process will be rewarded with an efficient and well-tuned database, not to mention happy users!" (Ken England, "Microsoft SQL Server 2000 Performance Optimization and Tuning Handbook", 2001)

"As the least conscious layer of the user experience, the conceptual model has the paradoxical quality of also having the most impact on usability. If an appropriate conceptual model is faithfully represented throughout the interface, after users recognize and internalize the model, they will have a fundamental understanding of what the application does and how to operate it." (Bob Baxley, "Making the Web Work: Designing Effective Web Applications", 2002) 

"A road plan can show the exact location, elevation, and dimensions of any part of the structure. The map corresponds to the structure, but it's not the same as the structure. Software, on the other hand, is just a codification of the behaviors that the programmers and users want to take place. The map is the same as the structure. […] This means that software can only be described accurately at the level of individual instructions. […] A map or a blueprint for a piece of software must greatly simplify the representation in order to be comprehensible. But by doing so, it becomes inaccurate and ultimately incorrect. This is an important realization: any architecture, design, or diagram we create for software is essentially inadequate. If we represent every detail, then we're merely duplicating the software in another form, and we're wasting our time and effort." (George Stepanek, "Software Project Secrets: Why Software Projects Fail", 2005)

"Developing fewer features allows you to conserve development resources and spend more time refining those features that users really need. Fewer features mean fewer things to confuse users, less risk of user errors, less description and documentation, and therefore simpler Help content. Removing any one feature automatically increases the usability of the remaining ones." (Jakob Nielsen, "Prioritizing Web Usability", 2006)

"The role of conceptual modelling in information systems development during all these decades is seen as an approach for capturing fuzzy, ill-defined, informal 'real-world' descriptions and user requirements, and then transforming them to formal, in some sense complete, and consistent conceptual specifications." (Janis A Burbenko jr., "From Information Algebra to Enterprise Modelling and Ontologies", Conceptual Modelling in Information Systems Engineering, 2007) 

"We tend to form mental models that are simpler than reality; so if we create represented models that are simpler than the actual implementation model, we help the user achieve a better understanding. […] Understanding how software actually works always helps someone to use it, but this understanding usually comes at a significant cost. One of the most significant ways in which computers can assist human beings is by putting a simple face on complex processes and situations. As a result, user interfaces that are consistent with users’ mental models are vastly superior to those that are merely reflections of the implementation model." (Alan Cooper et al,  "About Face 3: The Essentials of Interaction Design", 2007)

"Conceptual models are best thought of as design-tools - a way for designers to straighten out and simplify the design and match it to the users’ task-domain, thereby making it clearer to users how they should think about the application. The designers’ responsibility is to devise a conceptual model that seems natural to users based on the users’ familiarity with the task domain. If designers do their job well, the conceptual model will be the basis for users’ mental models of the application." (Jeff Johnson & Austin Henderson, "Conceptual Models", 2011)

"A conceptual model of an interactive application is, in summary: the structure of the application - the objects and their operations, attributes, and relation-ships; an idealized view of the how the application works – the model designers hope users will internalize; the mechanism by which users accomplish the tasks the application is intended to support." (Jeff Johnson & Austin Henderson, "Conceptual Models", 2011)

"The conceptual model is not the users’ mental model of the application. […] users of an application form mental models of it to allow them to predict its behavior. A mental model is the user’s high-level understanding of how the application works; it allows the user to predict what the application will do in response to various user-actions. Ideally, a user’s mental model of an application should be similar to the designers’ conceptual model, but in practice the two models may differ significantly. Even if a user’s mental model is the same as the designer’s conceptual model, they are distinct models." (Jeff Johnson & Austin Henderson, "Conceptual Models", 2011)

"Heuristics are simplified rules of thumb that make things simple and easy to implement. But their main advantage is that the user knows that they are not perfect, just expedient, and is therefore less fooled by their powers. They become dangerous when we forget that." (Nassim N Taleb, "Antifragile: Things that gain from disorder", 2012)

"If the user can’t understand it, the design and the designer have failed." (Joel Katz, "Designing Information: Human factors and common sense in information design", 2012)

"Successful information design in movement systems gives the user the information he needs - and only the information he needs - at every decision point." (Joel Katz, "Designing Information: Human factors and common sense in information design", 2012)

"For an infrequent action to become a habit, the user must perceive a high degree of utility, either from gaining pleasure or avoiding pain." (Nir Eyal, "Hooked: How to Build Habit-Forming Products", 2014)

"To change behavior, products must ensure the user feels in control. People must want to use the service, not feel they have to." (Nir Eyal, "Hooked: How to Build Habit-Forming Products", 2014) 

"User habits are a competitive advantage. Products that change customer routines are less susceptible to attacks from other companies." (Nir Eyal, "Hooked: How to Build Habit-Forming Products", 2014)

"Users who continually find value in a product are more likely to tell their friends about it." (Nir Eyal, "Hooked: How to Build Habit-Forming Products", 2014) 

"When designers intentionally trick users into inviting friends or blasting a message to their social networks, they may see some initial growth, but it comes at the expense of users' goodwill and trust. When people discover they've been duped, they vent their frustration and stop using the product." (Nir Eyal, "Hooked: How to Build Habit-Forming Products", 2014)

"Once we understand our user's mental model, we can capture it in a conceptual model. The conceptual model is a representation of the mental model using elements, relationships, and conditions. Our design and final system will be the tangible result of this conceptual model." (Pau Giner & Pablo Perea, "UX Design for Mobile, 2017)

"A 'stream' is the continuous flow of work aligned to a business domain or organizational capability. Continuous flow requires clarity of purpose and responsibility so that multiple teams can coexist, each with their own flow of work. A stream-aligned team is a team aligned to a single, valuable stream of work; this might be a single product or service, a single set of features, a single user journey, or a single user persona." (Matthew Skelton & Manuel Pais, "Team Topologies: Organizing Business and Technology Teams for Fast Flow", 2019)

"Documentation is a practice concerned with all the processes involved in transferring documents from sources to users." (Brian C Vickery)

"This is generally true: any sizeable piece of program, or even a complete program package, is only a useful tool that can be used in a reliable fashion, provided that the documentation pertinent for the user is much shorter than the program text. If any machine or system requires a very thick manual, its usefulness becomes for that very circumstance subject to doubt!" (Edsger W. Dijkstra, "On the reliability of programs")

05 October 2007

Taiichi Ohno - Collected Quotes

"Autonomation [automation with a human touch] changes the meaning of management as well. An operator is not needed while the machine is working normally. Only when the machine stops because of an abnormal situation does it get human attention. As a result, one worker can attend several machines, making it possible to reduce the number of operators and increase production efficiency. [...] Implementing autonomation is up to the managers and supervisors of each production area. The key is to give human intelligence to the machine and, at the same time, to adapt the simple movement of the human operator to the autonomous machines." (Taiichi Ohno, "Toyota Production System: Beyond Large-Scale Production", 1978)

"Autonomation [..] performs a dual role. It eliminates overproduction, an important waste in manufacturing, and prevents the production of defective products. To accomplish this, standard work procedures, corresponding to each player's ability, must be adhered to at all times." (Taiichi Ohno, "Toyota Production System: Beyond Large-Scale Production", 1978)

"'Efficiency', in modern industry and business in general, means cost reduction." (Taiichi Ohno, "Toyota Production System: Beyond Large-Scale Production", 1978)

"Establishing (1) a production flow and (2) a way to maintain a constant supply of raw materials from outside for parts to be machined was the way the Toyota, or Japanese, production system should be operated." (Taiichi Ohno, "Toyota Production System: Beyond Large-Scale Production", 1978)

"I feel the most important point in common between sports and work is the continuing need for practice and training. It is easy to understand theory with the mind; the problem is to remember it with the body. The goal is to know and do instinctively. Having the spirit to endure the training is the first step on the road to winning." (Taiichi Ohno, "Toyota Production System: Beyond Large-Scale Production", 1978)

"In a production plant operation, data are highly regarded - but I consider facts to be even more important. When a problem arises, if our search for the cause is not thorough, the actions taken can be out of focus. This is why we repeatedly ask why. This is the scientific basis of the Toyota system." (Taiichi Ohno, "Toyota Production System: Beyond Large-Scale Production", 1978)

"Just-in-time means that, in a flow process, the right parts needed in assembly reach the assembly line at the time they are needed and only in the amount needed. A company establishing this flow throughout can approach zero inventory." (Taiichi Ohno, "Toyota Production System: Beyond Large-Scale Production", 1978)

"Needs and opportunities are always there. We just have to drive ourselves to find the practical ones." (Taiichi Ohno, "Toyota Production System: Beyond Large-Scale Production", 1978)

"The first rule of kanban is that the later process goes to the earlier process to pick up products. This rule was derived from need and from looking at things upside-down, or from the opposite standpoint." (Taiichi Ohno, "Toyota Production System: Beyond Large-Scale Production", 1978)

"We have eliminated waste by examining available resources, rearranging machines, improving machining processes, installing autonomous systems, improving tools, analyzing transportation methods, and optimizing the amount of materials at hand for machining. High production efficiency has also been maintained by preventing the recurrence of defective products, operational mistakes, and accidents, and by incorporating workers' ideas. All of this is possible because of the inconspicuous standard work sheet." (Taiichi Ohno, "Toyota Production System: Beyond Large-Scale Production", 1978)

"When the problem is clearly understood, improvement is possible." (Taiichi Ohno, "Toyota Production System: Beyond Large-Scale Production", 1978)

"When thinking about the absolute elimination of waste, keep the following two points in mind: (1) Improving efficiency makes sense only when it is tied to cost reduction. To achieve this, we have to start producing only the things we need using minimum manpower. (2) Look at the efficiency of each operator and of each line. Then look at the operators as a group, and then at the efficiency of the entire plant (all the lines). Efficiency must be improved at each step and, at the same time, for the plant as a whole." (Taiichi Ohno, "Toyota Production System: Beyond Large-Scale Production", 1978)

"Costs do not exist to be calculated. Costs exist to be reduced." (Taiichi Ohno) 

"Let the flow manage the processes, and not let management manage the flow." (Taiichi Ohno) 

"Knowledge is something you buy with the money. Wisdom is something you acquire by doing it." (Taiichi Ohno) 

"Machines do not break down; people cause them to break." (Taiichi Ohno) 

"People who can’t understand numbers are useless. […] However, people who only look at the numbers are the worst of all." (Taiichi Ohno) 

"The production line that never stops is either excellent or terrible." (Taiichi Ohno) 

"To understand means to be able to do." (Taiichi Ohno) 


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