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An individual customer will have many requirements (or aspirations, or expectations, or desires) of a product or service.  Some of these requirements will be related, some distinct, and some may even be mutually exclusive.  Some requirements will conflict but may not be mutually exclusive.

There are likely to be several design choices available, to fulfil these requirements.

An optimum product or service is the one that best achieves these requirements.

In addition, a product to fulfil the requirements of several customers is likely to require compromise and optimisation.

Hierarchy of requirements

There is often an hierarchy of requirements.

Consider vehicle safety:

  • Safety is achieved through (example:) vehicle crumple zones, airbag & seatbelt operation, anti-lock brakes, passenger-cabin strength, and dashboard & steering-wheel design.

Accordingly, maximum safety is achieved with the maximum combined influence of these features, not by individual maximisation of one or more features.

Customers do not necessarily identify or state main requirements.  Rather, there may be a concentration on detailed, sub-requirements.  A good VOC process will identify and understand main requirements as well as detailed sub-requirements.


Product reliability is often a stated customer requirement.  However, the reason for improved reliability is sometimes lost.

Reliability offers combination of:

  • safety
  • reduced cost of ownership
  • freedom to use the product as intended
  • developing reputation

Reliability, in this context, is a sub-requirement.  Safety, cost-of-ownership, unrestricted use and trust are higher level requirements.  Accordingly, they should be maximised, not reliability.

Market Segmentation

When many, diverse customers are being considered, it may not be appropriate to design a single product or service to meet their needs.  Rather, distinct groups may be apparent.

Optimially identifying groups, their size, scope and requirements, is a science in itself.  It is beyond the scope of this module.

Marketing Management in Changing Times, Webster, Frederick E., Marketing Management; Jan/Feb2002, Vol. 11 Issue 1, p18