1. Introduction

2. Crowdsourcing Aspects

3. A Graph Framework of the QCC Research

4. Modelling Worker Ability

5. Modelling Worker Expertise and Question Difficulty

6. Modelling Worker Preferences and Question Subjectivity

7. Modelling Worker Motivation and Worker Contexts

8. Modelling Worker Expertise and Contexts

9. Modelling Worker Motivation, Question Difficulty and Contexts

10. Modelling Worker Ability, Question Difficulty and Contexts

11. Modelling Worker Expertise, Question Difficulty and Response Relationships

12. Summary and Discussion