Potential customers have spoken and unspoken requirements and aspirations.  They may also express a spoken priority or importance to particular requirements.

However, their spoken priorities are not necessarily a true reflection of their purchasing decisions.

• Customers may state that "safety is the number-1 priority" and yet will purchase a product with low safety.
• Customers may state that "the total cost of ownership is more important than the purchase price" and yet base their choice on purchase price.

In addition, the customer may not be able to articulate priorities or importance to particular features.

Therefore, a method is required to allow product and service designers to fully understand the priorities and purchasing behaviour of potential customers.

Conjoint analysis, by asking potential customers to repeatedly choose between product or service alternatives, enables this understanding.

• Alternatives may be presented in text, in pictures, in mock-up, in simulation; indeed, in the form best able to allow potential customers to appreciate what is being offered.
• Combinations of features are amalgamated within each alternative, using orthogonal array design; thus allowing the influence of each feature to be individually identified.
• Checks for potential customers manipulating the outcome may also be integrated in the survey.

Conjoint analysis was derived from psychological literature covering information processing and complex decision-making.

The methodology of Conjoint Analysis can be found in Analyzing decision making : metric conjoint analysis, Jordan J. Louviere