The Refined Kano’s Model andits Application

CHING-CHOW YANG

Chung-Yuan Christian University, Taiwan, Republic of China

ABSTRACT Kano’s model of five categories of quality attributes – attractive, one-dimensional,must-be, indifferent, and reverse quality – is widely used by industries and researchers.However, the model has a deficiency that prevents firms from precisely evaluating the influencesof quality attributes. The weakness is a failure to take account of the degree of importanceaccorded to certain quality elements by customers. Kano’s model can be refined. The presentstudy adds the importance of quality attributes and, in so doing, the refined model divides Kano’sfirst four categories into eight categories – highly attractive and less attractive, high value-addedand low value-added, critical and necessary, and potential and care-free. Based on the refinedmodel, firms can obtain a more accurate understanding of the quality attributes from thecustomer’s perspective, and can thus make more precise quality decisions. In addition tomodifying Kano’s model, the present study also develops an importance–satisfaction (I–S)model. By integrating the refined Kano’s model and the I–S model firms can gather even morevaluable information on quality decisions. The refined Kano’s model and the I–S model areillustrated with a case study.

KEY WORDS: Kano’s model, importance–satisfaction model, highly attractive attribute, highvalue-added attribute, critical attribute

Introduction

To sustain competitiveness and long-term profitability, companies devote themselves not

only to the attraction of new customers, but also to the retention of old customers with a

view to a continuing business relationship through incremental increases in purchases and

the maintenance of customer loyalty (Gorst et al., 1998). Several studies have demon-

strated that high loyalty and customer retention are associated with increased intention

of future purchases (Eklof & Westlund, 1998), and that customer loyalty is dependent

on the customer’s perception of the quality of the goods or services provided (Gorst

et al., 1998; Sirohi et al., 1998). Industries therefore pursue quality in product and

service in order to satisfy their customers.

Total Quality Management

Vol. 16, No. 10, 1127–1137, December 2005

Correspondence Address: Ching-Chow Yang, Department of Industrial Engineering, Chung-Yuan Christian

University, Taiwan, Republic of China. Email: chinchow@cycu.edu.tw

1478-3363 Print=1478-3371 Online=05=101127–11 # 2005 Taylor & FrancisDOI: 10.1080=14783360500235850

In the past two decades, industries have implemented a range of quality management

systems and standards, such as QCC, ISO 9000, TQM, and so on. The aims of these

quality activities are to achieve customer satisfaction (Kano et al., 1996; Kondo, 2001)

and to win their long-term trust by creating products and supplying services that fulfil

customer requirements and exceed their expectations. Indeed, the pursuit of customer

satisfaction and loyalty should be the main concern of all companies (Gorst et al., 1998).

In the past, customer satisfaction has been perceived in one-dimensional terms – the

greater the fulfilment of desired quality attributes, the higher would be customer satis-

faction. However, there are some quality attributes that fulfil individual customer expec-

tations to a great extent without necessarily implying a higher level of customer

satisfaction (Matzler & Hinterhuber, 1998). Several studies have therefore attempted to

link the physical and psychological aspects of quality to see how specific attributes of a

product or service actually relate to customer satisfaction or dissatisfaction, where the

physical aspect is concerned with the physical state or extent of the specific attributes,

and the psychological aspect is related to the customer’s subjective response in terms of

personal satisfaction (Schvaneveldt et al., 1991). Similarly, Kano et al. (1984) considered

two aspects of any given quality attribute – an objective aspect involving the fulfilment of

quality and a subjective aspect involving the customers’ perception of satisfaction. Kano’s

model is illustrated in Figure 1.

Using this model, quality attributes can be divided into five categories as follows:

. attractive quality attribute: an attribute that gives satisfaction if present, but that

produces no dissatisfaction if absent;

. one-dimensional quality attribute: an attribute that is positively and linearly related to

customer satisfaction – that is, the greater the degree of fulfilment of the attribute, the

greater the degree of customer satisfaction;

Figure 1. Kano’s model of quality attributes

1128 C.-C. Yang

. must-be quality attribute: an attribute whose absence will result in customer dissatis-

faction, but whose presence does not significantly contribute to customer satisfaction;

. indifferent quality attribute: an attribute whose presence or absence does not cause any

satisfaction or dissatisfaction to customers; and

. reverse quality attribute: an attribute whose presence causes customer dissatisfaction,

and whose absence results in customer satisfaction.

Questionnaire surveys of customers can be used to categorize quality attributes (Kano

et al., 1984; Bolster et al., 1993). Once quality attributes are categorized, products and

services can be designed to meet the different requirements for each quality attribute,

according to its category. It is critical to identify must-be quality attributes and to meet

demand for these at a minimum threshold level at least. Firms must also do their best

on the one-dimensional attributes – which are typically articulated by customers as

being a functionality they would desire. The attractive quality attributes can be selected

as competitive weapons to draw the attention of customers, especially new customers

(Rao et al., 1997). Using Kano’s model, quality attributes that have the greatest influence

on customer satisfaction can therefore be identified, and these can then be used to focus on

priorities for product or service development and improvement (Hinterhuber et al., 1997;

Matzler & Hinterhuber, 1998).

Several researchers have studied Kano’s model. Kano et al. (1984) empirically con-

firmed the applicability of their model for quality attributes of television product and

other manufactured goods. Miyakawa & Wong (1989) studied Kano’s model in manufac-

tured goods. Schvaneveldt et al. (1991) explored the applicability of Kano’s model to four

mass-market services – retail banking, cleaning services, family restaurants, and super-

markets. Matzler & Hinterhuber (1998) demonstrated the applicability of Kano’s model,

in combination with quality function deployment, using a case study from the ski industry.

Sa Moura & Saraiva (2001) used Kano’s analysis to develop an ideal kindergarten.

The Refined Kano’s Model

The most useful applications of Kano’s model are in the area of product and service devel-

opment and improvement. However, trade-offs are sometimes necessary. If two product

requirements cannot be met simultaneously for technical or financial reasons, firms

must consider the criteria that have the greatest influence on customer satisfaction

(Matzler & Hinterhuber, 1998). Usually, for any quality attribute, its influence on custo-

mer satisfaction is closely related to the degree of importance attached to it by customers

(Kristensen et al., 1992). For example, in a car, an automatic gearbox and a luggage carrier

are both attractive quality requirements. However, most customers consider an automatic

gearbox to be more important than a luggage carrier. Therefore, adding an automatic

gearbox will create greater customer satisfaction than adding a luggage carrier. Kano’s

model can therefore be refined by taking into account the importance of certain quality

attributes.

With respect to the must-be quality attributes, if such a quality attribute is also found

to have high importance in the estimation of customers, this quality attribute is not only

a necessary quality requirement but also a critical quality requirement. In contrast, if a

must-be quality attribute is considered less important, it can be defined as a necessary

quality requirement, but without being considered critical.

The Refined Kano’s Model and its Application 1129

With respect to one-dimensional quality attributes, increasing such attributes will raise

customer satisfaction. A one-dimensional quality attribute is therefore a value-added

quality attribute. It is therefore possible to define some one-dimensional quality attributes

with high importance as high value-added quality attributes, whereas others can be classed

as low value-added attributes.

For the attractive quality attributes, those with high importance can be classified as

highly attractive quality attributes, whereas those of lesser importance can be classified

as less attractive quality attributes.

The indifferent quality attributes are referred to in this study as care-free quality attri-

butes. However, if an indifferent quality attribute does possess higher importance than

another, it can be defined as a potential quality attribute because it does have some poten-

tial to attract customers. The indifferent quality attributes can therefore be classed as care-

free or potential, depending on their degree of importance.

Table 1 lists the redefined categories of quality attributes obtained by refining Kano’s

model. In Figure 2, curves are used to illustrate the means of the redefinitions of quality

attributes.

Table 1. Categories of quality attributes in unrefined and refined Kano’s model

Categories of

quality attributes

in Kano’s model

Categories of quality

attributes with high importance

in refined model

Categories of quality

attributes with low importance

in refined model

Attractive Highly attractive Less attractiveOne-dimensional High value-added Low value-addedMust be Critical NecessaryIndifferent Potential Care-free

Figure 2. Refined Kano’s model of quality attributes

1130 C.-C. Yang

The redefinitions of the categories of quality attributes according to the refined model

allow firms to make quality decisions with more precision. The following descriptions

illustrate the application of the refined model.

1. Kano’s attractive attributes

Highly attractive quality attributes

These are good weapons for firms to attract potential customers. These represent

strategic attribute offerings.

Less attractive quality attributes

Because these have little attraction to customers, these quality attributes can be

discarded if cost considerations demand this.

2. Kano’s one-dimensional attributesHigh-value-added quality attributes

These make a high contribution to customers’ satisfaction. They therefore can lead to

increased revenue. Firms should therefore make efforts to provide such attributes to

customers.

Low value-added quality attribute

These attributes make less contribution to customer satisfaction. But firms cannot

afford to ignore these attributes. The firms also need to avoid providing too less

level of these attributes to dissatisfied customers.

3. Kano’s must be quality attributes

Critical quality attributes

These are essential to customers. Firms must provide sufficient fulfilment of these

attributes to customers.

Necessary quality attributes

Firms can meet these at a required level to avoid dissatisfying customers.

4. Kano’s indifferent quality attributes

Potential quality attributes

These attributes will gradually be coming the attractive attributes. Firms can consider

providing these as strategic weapons to attract customers in the future.

Care-free quality attributes

If necessary, firms need not offer these attributes in view of cost considerations.

These brief descriptions demonstrate how the refined Kano’s model can help firms make

accurate decisions on quality planning.

Applications

A Practical Example of the Refined Model

The author has conducted several kinds of surveys for many companies, one of which is

a home-appliance manufacturer. The survey for this company covered the product quality

of various goods including an air-conditioner, a refrigerator, a washing machine, and a

television, together with service quality associated with these products. In this article,

the example of the air-conditioner is used for further discussion of the application of

the refined Kano’s model.

The Refined Kano’s Model and its Application 1131

A total of 20 key customers were first interviewed, including the end users and the

consignees of these home appliances. At the same time, the nominal group method was

used to conduct two panel discussions. The participants included service personnel,

sales personnel, and the supervisors from the quality-assurance division and sales division.

The purpose of customer interviews and internal panel discussion was to determine the

quality attributes to be contained in the questionnaire. As a result, 24 quality attributes

of the air-conditioner were developed for study.

Three kinds of questionnaires were designed:

. the importance of quality attributes;

. the satisfaction of quality attributes; and

. the categorization of attributes according to Kano’s model.

For the first two surveys, Likert-type 5 scales were used. For the study of Kano’s model,

the method suggested by Kano et al. (1984) was used to design the questionnaire. The

questionnaires were mailed out to 1400 customers randomly and 150 valid questionnaires

were returned.

The 24 quality attributes are listed in Table 2. The degrees of importance were assessed

into two categories – ‘high’ importance if the degree of importance was greater than the

mean for the 24 quality attributes, and ‘low’ if below the mean. This allowed classification

of the categories according to the refined Kano’s model (see sixth column of Table 2).

(The final column in Table 2 – the ‘category in the I–S model’ – is explained later in

this paper.)

The first 12 attributes are above the mean and are therefore classed as being of ‘high

importance’. Most of these attributes are one-dimensional, due to the features of these

attributes. As with all one-dimensional attributes, the greater the extent of this attribute,

the greater the customer perception of satisfaction. According to the refined model,

these one-dimensional attributes of high importance are categorized as high value-

added. Of the first 12 attributes, only three belonged to the must-be category. They are

redefined in the refined model as critical attributes.

Among the attributes of lesser importance (numbers 13 to 24 in Table 2), five are one-

dimensional, and are therefore redefined as low value-added attributes in the refined

model. There are four attractive attributes, and these are therefore re-categorized as less

attractive attributes. Only one must-be attribute with low importance is identified in this

research. This becomes a necessary attribute in the refined model. There are two attributes

identified as indifferent, now categorized as care-free attributes according to the refined

model.

It is not difficult to understand that one-dimensional attributes and attractive attributes

can be ranked as being of high importance or low importance. The situation with must-be

attributes is not as obvious. It might seem that these should all be of high importance.

Indeed, most of those must-be attributes are of high importance – but not all. It is possible

for an attribute to be required, but still not rank highly in overall importance to consumers.

In the present research, only one attribute (the guard net for the fin of the air-conditioner)

was classified as being necessary (that is, must-be, but with low importance).

The advantage of the refined model over the unrefined Kano’s model is shown by the

following example. The attributes ‘compressor noise’ and ‘free wind control and auto-

louver function’ are both categorized as one-dimensional attributes according to the

1132 C.-C. Yang

Table 2. Air-conditioner quality attributes

Ranking Quality attribute

Importance

(mean)

Satisfaction

(mean)

Category in

Kano’s model

Category in

refined Kano’s

model

Category in

I–S model

1 Compressor noise 4.46 3.46 One-dimensional High value-added To be improved2 Durability of fan motor 4.33 3.88 One-dimensional High value-added Excellent3 Outlet noise of air-conditioner 4.33 3.54 One-dimensional High value-added To be improved4 Anti-erosion of heat exchanger 4.32 3.76 One-dimensional High value-added Excellent5 Stainless base 4.15 3.90 Must-be Critical Excellent6 Ease of maintenance and cleaning 4.07 3.75 One-dimensional High value-added Excellent7 Comfort 4.06 3.72 One-dimensional High value-added Excellent8 Air-cleaning efficiency 4.04 3.65 One-dimensional High value-added To be improved9 Temperature display (room and setting) 4.02 3.87 Must-be Critical Excellent

10 Drop protection and drainage 3.97 3.75 One-dimensional High value-added Excellent11 Inverter compressor 3.95 3.63 Must-be Critical To be improved12 Negative ions 3.95 3.76 Attractive Highly attractive Excellent13 Price 3.94 3.40 One-dimensional Low value-added Care-free14 Material accordance of base and internal

compressor surrounding3.93 3.71 Attractive Less attractive Surplus

15 Free wind control and auto louver function 3.92 3.65 One-dimensional Low value-added Care-free16 Cleaning instructions 3.92 3.54 Attractive Less attractive Care-free17 Guard net for fin 3.86 3.79 Must-be Necessary Surplus18 Ease of portability and installation 3.80 3.65 One-dimensional Low value-added Care-free19 Attractiveness and design for external looks 3.77 3.73 One-dimensional Low value-added Surplus20 Wired and wireless control function 3.68 3.77 Attractive Less Attractive Surplus21 Four key functions in one 3.64 3.60 Attractive Less attractive Care-free22 Universal remote control 3.57 3.65 Indifferent Care-free Care-free23 Cleanliness of surface 3.56 3.66 One-dimensional Low value-added Care-free24 Pre-order function of starting time 3.35 3.55 Indifferent Care-free Care-free

Mean 3.941 3.678

Note: Ranking is according to level of importance. If two or more attributes have the same importance level, the attribute with a smaller deviation is ranked higher.

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rules of Kano’s model. According to the unrefined model, a firm will pay similar attention

to these two attributes. However, when the firm recognizes the categories of these attri-

butes according to the refined model, the ‘compressor noise’ attribute is seen to be a

high value-added attribute (and therefore of greater significance to the firm), whereas

the ‘wind control and auto-louver function’ is of low value-added (and therefore of lesser

importance to the firm). As a result, the firm will adopt very different strategies towards the

two attributes.

Business management normally focuses on improvements to quality elements that are

unsatisfactory in the estimation of customers. However, according to the refined model,

this is not the only consideration. Firms can simultaneously take care of the satisfaction

level of quality attributes and their degree of importance. Firms can thus obtain much valu-

able information for improvements from a comparison between the satisfaction levels and

the degree of importance of quality attributes. This is a very important concept, since cus-

tomers evaluate quality by using quality attributes that they recognize as important

(Deming, 1986; King, 1987; Headley & Choi, 1992). If customers’ satisfaction on these

important attributes falls to a low level, the overall quality evaluation from customers

can be very poor. Therefore, those quality attributes which customers consider to be

highly important and which have a lower satisfaction level are those that management

needs to address as a first priority for improvements.

The Importance–Satisfaction Model

The above discussion leads to the development of a model referred to as the importance–

satisfaction model (I–S Model) (Yang, 2003). This is illustrated in Figure 3.

In this model, the horizontal dimension shows the degree of importance of a quality

attribute, and the vertical dimension shows the satisfaction level of the quality attribute.

The order pair (importance scale, satisfaction scale) can then be located on the

Figure 3. The importance–satisfaction model

1134 C.-C. Yang

coordinates. The means of the importance scale and the satisfaction scale can be used to

divide the coordinate into four areas, as follows:

. I. Excellent area: The attributes located in this area are those that customers considered

to be important, and for which the performance is satisfactory to customers. Retention

of customers requires that performance in these attributes be continued.

. II. To be improved area: The quality attributes listed in this area are those considered as

important to customers but for which the performances have not met with expectation.

The company must focus on these attributes and make improvements immediately.

. III. Surplus area: The attributes listed in this area are not very important to customers,

but the perceptions of customers are quite satisfactory. The company can put these

quality attributes aside. If the company needs to cut costs, these are the attributes that

can be eliminated without incurring a significant negative impact on the customer

satisfaction.

. IV. Care-free area: These quality attributes are those about which customers have a

lower satisfaction level, but which they also rank as being less important. The

company does not need to worry about these attributes, because these items have less

impact on the whole quality-evaluation process.

Even though this importance–satisfaction model is a simple structure, it can neverthe-

less provide much useful information about a company’s quality performance. The model

can be applied to the empirical study described above. The last column of Table 2 shows

the I–S category for each of the quality attributes discussed in the empirical study. The

results are displayed in Figure 4.

Figure 4. The display of the I–S model for Table 2

The Refined Kano’s Model and its Application 1135

From the data in Table 2 and the display of Figure 4, much valuable information can be

obtained. The important points to be noted are as follows.

. Most of the must-be quality attributes are found to be important, but not all. The attri-

bute dealing with the guard for the fin of the air conditioner is treated as must-be, but it is

not considered to be important. It is therefore classified as a necessary attribute.

. For one-dimensional attributes and attractive attributes, some are considered to be

important and some are not.

. In the to be improved area, three attributes are high value-added, but only one attribute

is critical.

. Although the attribute dealing with the price of the air-conditioner is located in the care-

free area, it is very close to the to be improved area. As a result, the company must still

pay attention to this attribute.

. There are three critical attributes – two are located in the excellent area. This means

that company has ascertained the critical nature of these attributes, and has also pro-

vided them to a sufficient extent.

. There is one highly attractive attribute that is located in the excellent area. This is the

attribute relating to ‘negative ions’. This therefore represents a very good competitive

weapon. It is of interest that the company has also emphasized the importance of this

point in its advertising.

. There are two less attractive attributes (denoted by numbers 14 and 20 in Table 2) that

are located in the surplus area. If the company wants to reduce costs, these attributes can

be considered.

. There are only two indifferent attributes (denoted by numbers 22 and 24). These are

listed in the care-free area, they are also identified as care-free attributes in the

refined model, and therefore the company has no need to pay much attention to these

two attributes.

Analyses of this type are very useful and valuable for the company. The company can

make better decisions with respect to product quality by referring to the models presented

here.

Conclusion

Kano’s model is a good tool for industries to use in analysing key quality attributes in

order to make better decisions on quality strategies. But the unrefined model has a

deficiency in that the degree of importance of quality attributes is neglected. Customers

are the only judges of quality in goods and services, and they evaluate the quality by

using several attributes that are important from their perspective. Thus, degree of import-

ance is a critical dimension considered by customers when they are evaluating the quality

performance. On this basis, the present study has integrated this ‘importance’ concept into

Kano’s model – thus developing a new refined model. According to the refined Kano’s

model, quality attributes can be divided into more precise categories.

An increasing number of companies conduct surveys of customers. It is the contention

of this paper that firms can analyse the categories of quality attributes according to both the

refined Kano’s model and the I–S model. This enables firms to obtain much more valuable

1136 C.-C. Yang

information. The refined Kano’s model is not only a useful practical tool for industries, but

it is also a theoretical model for academic research.

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The Refined Kano’s Model and its Application 1137