Field implementation then becomes a source of requirements for future products, and the cycle repeats. Other techniques, such as focus groups, questionnaires, and surveys, may be employed. Additional information on potential product features may be obtained from user groups, from sales and marketing forces, from maintenance engineers and help lines, and from analysis of competitors' products. A stakeholder analysis should first be carried out to ascertain which parties' requirements should have a bearing on the design. Other stakeholders then must be involved in the design process.
Stakeholder analysis can radically change design acceptance criteria.
For example, with increasingly powerful and reliable telecommunications technology, maintenance costs are becoming a more significant cost factor. A new feature's value may need to be traded off against its potential to demand increased maintenance. User observation will be the designer's primary source for a model of the users' domain, main tasks, and priorities. Observation is especially helpful in studying work habits of which the users themselves may not have been aware such as work-arounds, failures, and exceptions. When looking for innovation, these breakdowns can be a rich source of new product ideas.