User Interaction {#15} influences:

• General product risks, market selection and user type
• Product design and validation
• Production tooling and testing
• Documentation
• All testing scenarios
• Product validation and reliability
• Regulatory, industrial  and legal standards
• Production processes
• Training, service, support, upgrades, bug correction
• Installation, calibration and maintenance
• Environmental compatibility
• Consumables, energy and fuel management
• Product acceptance vs. failure and good will
• End-of-Life requirements and procedures
•  (Product usability, user and testing interfaces, Industrial Design considerations, etc.)

For example, if the product provides normal and acceptable user interaction, but does not support proper interaction for testing, repair, installation, etc., then support costs will increase.