1. What is the rationale for using intent-to-treat (ITT) analysis in an RCT? What bias is likely to occur with the use of ITT?

2. You are conducting an observational study to understand if excessive alcohol use is a cause of depression. From previous studies, there is evidence that childhood trauma is a cause of alcohol use and a cause of depression. Please draw the DAG for the relationships described.

3. If you were to use a cohort study design to conduct the study described above, what must be true of everyone who participates at the start of the study (i.e. at the time of recruitment)? Why does this matter with regard to what you will measure in the study?