Prioritising service requirements with the Kano model.

Traditional ideas about quality have assumed that user satisfaction is simply proportional to how functional a product is. The Kano model – which was developed in 1984 by Professor Noriaki Kano – states that this is true only for some product features. The model classifies user preferences into five distinct categories: Delighters, Basic Needs, One-Dimensional, Indifferent and Reverse (we’ll describe these later).

In the past 30 years the Kano model has been used to prioritise product features. We believe that the model is a valuable tool to quantify requirements of a service from a user-centred perspective. In the diagram below, the One-Dimensional line graphs the situation in which user satisfaction is simply proportional to how functional the service is.

Kano-1

The vertical axis indicates how satisfied the user is, while the horizontal axis shows the level of implementation. According to the model some user requirements are not one-dimensional – there are ‘basic needs’ and ‘delighting’ elements. The ‘basic needs’ curve indicates aspects where the user is more dissatisfied when the product or service is less functional, but where the user’s satisfaction never rises above neutral no matter how functional the product or service becomes.

The ‘delighters’ curve indicates areas in which the user is more satisfied when the product or service is more functional but is not dissatisfied when the product or service is less functional.

Benefits are:

  1. Gaining a better understanding of product or service requirements
  2. Prioritising requirements for development activities
  3. Distinguishing market segment characteristics
  4. Aiding in the design trade-off process.

How it works – the Kano questionnaire

The user requirements are classified by a customised questionnaire. The questionnaire is best used in a structured interview with existing or potential users of the service.

Each question has two parts:

Kano-2

For each part of the question, the user can answer in the following ways:

For example:

Kano-3

The answers to both questions are classified into 6 different requirements according to the matrix below. The highlighted field represents the ‘paper bill’ example.

Kano-4

Delighters are criteria which have the greatest influence on how satisfied a user will be with a given service. They are neither explicitly expressed nor expected by the user. Fulfilling these requirements leads to more than proportional satisfaction. If they are not met, there is no feeling of dissatisfaction.

If Basic Needs are not fulfilled, the user will be extremely dissatisfied. The users take these requirements for granted, therefore their fulfillment will not increase satisfaction. These must-be requirements will only lead to a state of ‘not dissatisfied’. However if they are not fulfilled, the user will not be interested in the service at all.

With One-Dimensional requirements, user satisfaction is proportional to the level of fulfillment. The higher the level of fulfillment, the higher the user’s satisfaction and vice versa. One-dimensional requirements are usually explicitly demanded by the user.

A user may also be Indifferent to a quality element and would be plotted roughly along the horizontal axis. That is, the user is neither satisfied nor dissatisfied whether the service is dysfunctional or fully functional.

Reversed means that the service feature is not only not wanted by the user but that they even expect the reverse.

Questionable results emerge when there is a contradiction in the user’s answers to the questions. Questionable scores signify that the question was phased incorrectly, or that the person interviewed misunderstood the question or crossed out a wrong answer by mistake.

Skip this section – unless you’re a nerd and you really want to know how it works

The results of the questionnaire are analysed by frequency and summarized in a table (see below). The highest frequency defines which category (Delighter, One-Dimensional, Basic Needs or Indifferent) the service requirement falls into. In the below example ‘Ease of use’ was categorized as a Delighter by 60 percent of the respondents, ‘Price’ as a Basic Need by 40% and ‘Reliability’ by 55% as One-Dimensional.

Kano-5

To calculate the average Extent of satisfaction it is necessary to add the delighting and one-dimensional columns and divide by the total number of delighting, one-dimensional, basic needs, and indifferent responses. For the calculation of the average Extent of dissatisfaction you should add the Basic Needs and One-Dimensional columns and divide by the same factor.

Kano-6

These two measures tell you whether satisfaction can be increased by meeting a service requirement, or whether fulfilling this requirement merely prevents the user from being dissatisfied. The Extent of satisfaction ranges from 0 to 1; the closer the value to 1, the higher the influence on user satisfaction. The Extent of dissatisfaction ranges from 0 to -1. A value close to -1 means that if the feature is not met it causes significant dissatisfaction.

The graph below gives an example of how the results can be displayed.

Kano-7

For example: Offering ‘24/7 call centre support’ is unlikely to delight users and contribute to satisfaction. However, if users are in need for support after business hours, absence of this feature will cause significant dissatisfaction.

What are the implications?

The results of the questionnaire are analysed by frequency and summarized in a table (see below). The highest frequency defines which category (Delighter, One-Dimensional, Basic Needs or Indifferent) the service requirement falls into. In the below example ‘Ease of use’ was categorized as a Delighter by 60 percent of the respondents, ‘Price’ as a Basic Need by 40% and ‘Reliability’ by 55% as One-Dimensional.

 

Often product or service requirements are set up as a list of technical features that lack a user-centred point-of-view. The resulting products or services often contribute little to customer satisfaction or even lead to dissatisfaction when basic need are not fulfilled.

Using the Kano model helps to quantify and categorise to what extent a product or service influences user satisfaction. It serves as a guide to prioritise requirements in the design process.

On a generic level, the strategic implications are straightforward:

  • Fulfill all basic needs
  • Compete on one-dimensional requirements
  • Stand out from your competitors with delighting requirements

But, be aware that customer expectations change over time. Therefore a service feature that was delighting customers in the past might today just be considered as a basic need. Think of hotels offering free Wifi to their guests. Not so long ago this service was an unexpected and delighting feature. Nowadays this service offering has lost most of its delighting qualities as it has become a basic need for many guests to use the internet during their stay.

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