The Reﬁned Kano’s Model and
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 inﬂuences
of quality attributes. The weakness is a failure to take account of the degree of importance
accorded to certain quality elements by customers. Kano’s model can be reﬁned. The present
study adds the importance of quality attributes and, in so doing, the reﬁned model divides Kano’s
ﬁrst four categories into eight categories – highly attractive and less attractive, high value-added
and low value-added, critical and necessary, and potential and care-free. Based on the reﬁned
model, ﬁrms can obtain a more accurate understanding of the quality attributes from the
customer’s perspective, and can thus make more precise quality decisions. In addition to
modifying 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 more
valuable information on quality decisions. The reﬁned Kano’s model and the I–S model are
illustrated with a case study.
KEY WORDS: Kano’s model, importance–satisfaction model, highly attractive attribute, high
value-added attribute, critical attribute
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: firstname.lastname@example.org
1478-3363 Print=1478-3371 Online=05=101127–11 # 2005 Taylor & Francis
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
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
Table 1. Categories of quality attributes in unreﬁned and reﬁned Kano’s model
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 attractive
One-dimensional High value-added Low value-added
Must be Critical Necessary
Indifferent 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 attributes
High-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
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.
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
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
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
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
1 Compressor noise 4.46 3.46 One-dimensional High value-added To be improved
2 Durability of fan motor 4.33 3.88 One-dimensional High value-added Excellent
3 Outlet noise of air-conditioner 4.33 3.54 One-dimensional High value-added To be improved
4 Anti-erosion of heat exchanger 4.32 3.76 One-dimensional High value-added Excellent
5 Stainless base 4.15 3.90 Must-be Critical Excellent
6 Ease of maintenance and cleaning 4.07 3.75 One-dimensional High value-added Excellent
7 Comfort 4.06 3.72 One-dimensional High value-added Excellent
8 Air-cleaning efﬁciency 4.04 3.65 One-dimensional High value-added To be improved
9 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 Excellent
11 Inverter compressor 3.95 3.63 Must-be Critical To be improved
12 Negative ions 3.95 3.76 Attractive Highly attractive Excellent
13 Price 3.94 3.40 One-dimensional Low value-added Care-free
14 Material accordance of base and internal
3.93 3.71 Attractive Less attractive Surplus
15 Free wind control and auto louver function 3.92 3.65 One-dimensional Low value-added Care-free
16 Cleaning instructions 3.92 3.54 Attractive Less attractive Care-free
17 Guard net for ﬁn 3.86 3.79 Must-be Necessary Surplus
18 Ease of portability and installation 3.80 3.65 One-dimensional Low value-added Care-free
19 Attractiveness and design for external looks 3.77 3.73 One-dimensional Low value-added Surplus
20 Wired and wireless control function 3.68 3.77 Attractive Less Attractive Surplus
21 Four key functions in one 3.64 3.60 Attractive Less attractive Care-free
22 Universal remote control 3.57 3.65 Indifferent Care-free Care-free
23 Cleanliness of surface 3.56 3.66 One-dimensional Low value-added Care-free
24 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.
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
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
. 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
. 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
. 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
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
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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