Principal Stratification: novel declinations and uses

The Thesis is organized as follows. Chapter 1 illustrates the Principal Stratification framework and provides an extensive review of its common declinations and uses in contexts where it can be assumed that there is no interference between units. Chapter 2 reports the analyses of the Oyam Health Expenditures Study. Chapter 3 describes our proposal to adopt a Principal Stratification framework in the context of non-inferiority trials with non-adherence, also showing the simulation study results. Chapter 4 focuses on the problem of interference and explains our methodological proposal for the analysis of Clustered Encouragement Designs under network interference by using the Florentine study as an illustrative example. Chapter 5 concludes.