## Appendix A  
To evaluate the method as well as the software prototype, experts from the case study projects were asked to fill out the questionnaire below. Attendees were responsible for various tasks in case study projects, e.g., project coordination, conceptual design and development or production. The number of team members involved in each case study project varied, but did not exceed ten. The first part of the questionnaire (questions 1-5) is used to create an overview of the people who participated. Results are summarized below:  
* Professional background: All participants come from the field of mechanical engineering or industrial engineering. * Work experience: Participants have between 3 and 20 years of work experience (exception: one attendee had less than one year work experience). * Age: All participants are between 20 and 45 years old. The following diagrams show the results of questionnaire analysis, evaluated according to the following scale:  
* 2: Agree
* 1: Rather agree
* 0: Partly-partly
* \(-1\): Rather not agree
* \(-2\): Do not agree  
Diagrams show the range and mean value of the answers. Besides there are yes/no questions and open questions, which are answered in text form. **Theses on requirement changes**  
6. Requirement changes endanger the success of the project  
7. It is difficult to assess the effects of requirements changes realistically  
8. Before the OptiAMix project, requirements changes were already taken into account in the development process according to their importance  
9. Before the OptiAMix project, requirements changes were already handled systematically  
10. Before the OptiAMix project, requirements changes had already been handled preventively  
**Figure A1. ** Questionnaire results on area \"requirement changes (general)\". * [11] The method supports the identification of areas of influence on requirement changes
* [12] The three factors uncertainty, dynamic and relevance allow a meaningful prioritization of the areas of influence
* [13] The effort for the project-specific, manual assignment of main features to requirements for the network analysis is reasonable
* [14] The one-time expenditure for the elaboration or project-specific adaptation of the dependency matrix between main characteristics is acceptable for long-term application of the method
* [15] The method is used to identify all existing dependencies betweenrequirements
* [16] The determined risk of a requirement change using the method is realistic
* [17] The application of the method sensitizes the development team regarding the cross-departmental change effects
* [18] The application of the method leads to the identification of cross-departmental change risks that would otherwise haveremained undetected
* [19] The classification of the requirements in a risk portfolio supports interdepartmental communication within the development team
* [20] Based on the information about the change risk, efficiency-enhancing preventive measures can be initiated
* [21] More effective decisions on change implementation can be made based on change risk information
* [22] Based on the information about requirement dependencies, occuring changes can be integrated more efficiently
* [23] The risk of project failure is reduced by applying the method  
Figure 10: Questionnaire results on area “method for systematic assessment of requirement change risk”—Part I/II. 24. Yes/No Question: For which of the following elements is research/development needed to improve the quality of results? 24.1 Identification of the areas of influence  
24.2 Prioritisation of areas of influence  
24.3 Assignment of a representative area of influence per requirement  
24.4 Identification and weighting of the dependencies between the main features  
24.5 Assignment of a representative main feature per requirement  
24.6 Calculation of the risk of change based on priority and networking  
25. Open question: Which aspects need to be supplemented before an application in everyday development?