Developed by Pascal Trebin
One of the main goals when starting developing a product or service is to satisfy the customer, but how do you know which features to include and what the customer expects. In order to create a competitive product, it is of advantage to surprise the customer with not expected features. When starting a product or commissioning a product as a product manager, you have to find out what features should be included. There is a tool to figure it out and to measure satisfaction, it is called Kano model. This Article provides an overview, how to use it to find out the requirements, gives an example and represents advantages and disadvantages.
The Kano model is a method to scale the layers of quality and to achieve consumer satisfaction in a project or a product. The Model was published in 1978 by Noriaki Kano (*1940), a Professor of the Tokyo University of Science.  The theory is proposed to understand the relationship between customer satisfaction and quantitative measures. The requirement and the performance of the product or service derived from the different types, the model provides. The model gathers the needs of the customers to include them in the development of a product or service.  In a product development project it is recommended to use the Kano model to meet customer's needs and to determine requirements in an early project phase. The article provides the explanation of the Kano model, the application and how to make projects successful by involving it.
The model certainly represents a transfer and expansion of the two-factor theory (also known as the dual-factor theory or Herzberg's motivation-hygiene theory) of Herzberg (1959). Herzberg's theory figured the job satisfaction at the workplace out. The basic features (Kano) correspond in their definition to the hygiene factors (Herzberg), the performance characteristics and enthusiasm features according to Kano are comparable with the motivation factors (Herzberg).Kano has found that the requirements can be divided into different classes since the relationship between the fulfillment of a need and satisfaction or dissatisfaction is non-linear. Each class presents a different relationship to satisfaction, this means a product can give different types of satisfaction or dissatisfaction, depending on whether specific customer requirements are fulfilled or only partly or not at all.
The five quality elements
It is difficult to make quality tangible, every customer has a different perception of quality. Noriaki Kano published his idea to challenge this problem. The Kano model is a two-dimensional chart with the product functionality on the x-axis and the customer's satisfaction on the y-axis, it distinguishes five types of quality elements as followed (see Figure 1):
Must-be Quality Elements
Are essential and assumed for the customer. If the product does not fulfill these requirements, the customer will be dissatisfied but if it is fulfilled, the customer will not show up satisfaction or is not even interested in the product. The must-be curves flatten towards to the end, it means a bit of investment does not make the customer dissatisfied, but even more, invest cannot give the customer satisfaction. It is important to know as soon as an element has reached the must-be category, there is no need for invest anymore.
One-dimension Quality Elements
(also called Linear or Performance in the literature) Are conscious to the customer, eliminate dissatisfaction or achieve satisfaction depending on the degree of fulfillment, the higher the better. Every enhancement in the product or service regarding the performance gives the customer more satisfaction, but adding of functionality means adding of investment. Between the performance and the price a customer is willing to pay, is tight-knit. 
Attractive Quality Elements
Are not usually expected by the customer and do not disappoint them when not fulfilled. These attributes deliver satisfaction or enthusiasm and are the main elements for reaching a competitive advantage. The best effect shows a feature the customer not even knows before. 
Indifferent Quality Elements
Are not noticed by the customer or are not aware of it, they cannot give either satisfaction or dissatisfaction when fulfilled or not. These elements should be avoided as they involve costs and expenses which are not repaid.
Reverse Quality Elements
These elements cause satisfaction when absent and dissatisfaction when present. 
The habituation effect: From attractive to must-be over the time
It is important to understand, that the categories are not static, they adapt step by step. The quality elements are moving slightly over the time. Todays Must-be, have been Attractive for some years and the one-dimensional elements decrease steadily over the time. A habituation effect occurs (see Figure 2). Relating to the car examples below (see Examples), a man bought his first car, a BMW 120d and is planning to use it for 10 years. The car has 190 hp (one-dimension category), which is a lot for the young man and he is excited. After 10 years, the men decide to buy a new car, but he became accustomed to the power of the engine and will not be enthusiastic if the new car has 190 hp as well. The man choose the car because it also has seat heater, navigation and Bluetooth connection (attractive category), which convinced him. After a certain time, a related observation can be made. The features change for the man from ataractic to must-be. He will be dissatisfied if his next car comes without this features. 
|Example Car:||Example Flight:|
|Must-be||Breaks, Tires||Seat, Hand-luggage, Seatbelt|
|One-dimension||Horsepower, Fuel consumption, Acceleration||Food and Drinks, Space, Seating width,|
|Attractive||Head-Up Display, TV, Adaptive chassis||WiFi, Pillow, Blanket, Fresh Towel, Entertainment|
|Indifferent||Supplier of Windows||Design features|
|Reverse||Rusty spots, Flat tires||Canceled Flight|
Application of the Kano model
The explanations before conveyed a basic understanding about the Kano model and how it works. The following step shows an example how to use the Kano model in practice with several users and different features.
The basic and comfortable ways, applying the Kano Model, are doing Kano's evaluation sheet, a survey of the customers or an interview with two simple questions for every feature.
First, select the features carefully, take these, which provide you a significant benefit. The product might have many features, choosing the right ones will save time and effort. Second, select the right participants for the survey, they should be a demographic and logical group. At last, write two simple questions for every feature. 
A) How do you feel if that feature is present in the product? (functional)
B) How do you feel if that feature is not present in the product? (dysfunctional)
The respondents can only answer with the following replies:
1. I like it that way;
2. It must be that way;
3. I am neutral;
4. I can live with it that way;
5. I dislike it that way
When writing these questions you should pay attention to the following:
- A question should cover only one feature.
- The questions should be customer-specific and do not contain any technical terms, the customer might not understand.
- The time you take for the customer reflects the professional image of the company.
Based on the combination of responses to the functional and dysfunctional question the classification can be deduced (see Table 2). Questionable result answers are not taken into account during the evaluation.
|dysfunctional (feature absent)|
|1. like||2. must be||3. neutral||4. live with||5. dislike|
|functional (feature present)||1. like||Q||A||A||A||O|
|2. must be||R||I||I||I||M|
|4. live with||R||I||I||I||M|
|A: attractive||M: must be||O: one-dimension|
|R: reverse||I: indifferent||Q: questionable result|
An example for the evaluation, regarding the example from above: The young man is asked about his car. One question relates to the feature Bluetooth connection. His answer to the question A) is: I like it that way, and for the question B): I am neutral. This means the feature is attractive for him. If the same question will be done 10 years later, when he buys a new car the answer could be different, because of the habituation effect. The man could answer than for question A) I am neutral, and for question B) I dislike it that way. The attractive feature changed to a must-be feature.
Kano model for a successful project
1. Identify your customer's needs with the Kano model. What are they basically expect and what missing features make them dissatisfied.
2. Design your products or services according to the Kano model. Invest or hold up just the features, which deliver more satisfaction.
3. Know your attractive features and trying to develop steadily more of them to be innovative. 4. Watch your customers and the competition, to recognize when a feature turns to another element.
5. Identify and concentrate on sustainable attractive qualities, they make your product unique and provide further the customers' satisfaction. 
Advantages and Disadvantages
Advantages: In a product or service development it is important to find and to classify customer's needs. The Kano model helps to find and to understand them and to generate the requirements. A better understanding of requirements:
1. The most influenced product criteria on the customer satisfaction can be identified. Dividing product requirements into one-dimension, must-be and attractive dimensions are helpful to decide where to set the focus in the development. For example, it is advisable to improve the one-dimension and attractive elements instead of the must-be, which are on a satisfied level. This has more influence on the appreciable product quality and the satisfaction of the customer.
2. The Kano model can be used in trade-off situations, when two or more product requirements cannot be fulfilled at the same time, because of technical or financial issues. The feature with the higher impact on the customer's satisfaction can be chosen.
3. The requirements vary in customer segments, because of the different expectation to a product. It is possible to work on a tailored solution, which provides a high satisfaction level in every segment. 
4. Differentiation of market segment features. 
1. A full Kano analyze takes a lot of time, particularly the interview of the customers.
2. The model is limited to the customer’s perception, this means some features cannot be considered (e.g. support needs, non-functional requirements)
3. The model does not cover features the customer has not tried before. New innovations have to be tested to use the Kano model.
4. Cost either for the features to the development are not considered by Kano and must be analyzed in an extra analysis.
5. To formulate the customer requirement in the functional and dysfunctional style of the Kano model is very difficult.
The Kano model is a useful method to define the requirements on the basis of the customer's satisfaction. It can be recommended to every project. As a company, it is advantageous to know how a product feature affects product quality and, as a result, increases customer satisfaction and achieves long-term goals. In this article has tried to show how Kano’s model can be used and be interpreted. Thus, product development procedures can become more systematic, the advantages predominate. In addition, it is recommended to use different methods and tools for analyzing and prioritizing requirements, such as Six Thinking Hats, Brainstorming, Comparison in Pairs or House of Quality.
Attractive Quality and Must-be Quality - Kano, N.; et al. (1984)
Kano is the inventor of the Kano model and describes the model and how to use it in his original way.
Understanding customer needs through quantitative analysis of Kano's model - Wang, T.; et al. (2010)
Describes deeply the use of the Kano model and aims to help companies develop a better understanding of customer needs.
Customer-defined Quality - Pouliot, F. (1993)
Gives different views to the Kano model and is very critical.
- ↑ 1.0 1.1 Kano, N.; et al. (1984), Attractive Quality and Must-be Quality; Journal of the Japanese Society for Quality Control
- ↑ Lenz, H. J.; et al. (2010), Frontiers in Statistical Quality Control 9. Physica-Verlag Heidelberg, ISBN 978-3-7908-2379-0
- ↑ Herzberg, F.; et al. (1959), The motivation to work, Wiley, New York, NY
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Pouliot, F. (1993), Customer-defined Quality, Center for Quality of Management Journal Volume 2, Number 4
- ↑ 5.0 5.1 Ullman, D. G. (1997), The Mechanical Design Process, McGraw-Hill, Inc., U.S.A., pp. 105-108 ISBN 0-07-065756-4
- ↑ Brandt, D. R. (1988), How service marketers can ident- ify value-enhancing service elements. Journal of Services Marketing 2, 35–41.
- ↑ Randall Brandt, D. (1988), How service marketers can identify value‐enhancing service elements, Journal of Services Marketing, Vol. 2 Issue: 3, pp.35-41, https://doi.org/10.1108/eb024732
- ↑ Shen, D. (1993), Developing and Administering Kano Questionnaires on Kano’s Methods for Understanding Customer-defined Quality, Center for Quality of Management Journal
- ↑ Lee, Y. C.(2011), A new Kano's evaluation sheet, The TQM Journal, Vol. 23 Issue: 2, pp.179-195, https://doi.org/10.1108/17542731111110230
- ↑ own representation based on Berger, C., et al. (1993), Kano’s methods for understanding customer-defined quality, Center for Quality Management Journal, Vol. Fall
- ↑ Eriksson, M. (2013), Using The Kano Model To Prioritize Product Development, https://www.mindtheproduct.com/2013/07/using-the-kano-model-to-prioritize-product-development/
- ↑ Hinterhuber, H.H.; et al. (1998), How to make product development projects more successful by integrating Kano’s model of customer satisfaction into quality function deployment, Elsevier Science Ltd