Includes the three following peer-reviewed chapters: ○ PJ Giabbanelli & M Baniukiewicz. Navigating complex systems for policymaking using simple software tools. Chapter 2, pp. 21–40. ○ A Khademi, D Zhang, PJ Giabbanelli, S Timmons, C Lu, L Shi. An agent-based model of healthy eating with applications to hypertension. Chapter 3, pp. 43–58. ○ PJ Giabbanelli. Analyzing the complexity of behavioural factors influencing weight in adults. Chapter 10, pp. 163–181.