Assessment 1 (30%) DAGs
Assesses learning objectives 1, 2, 3, and 4
Available to students March 26th
Due Thursday April 9th at 1 pm at the start of class.
PART 1. DAG QUIZ (7 points)
The DAG below has various paths that connect nodes (nodes are variables like X or Y or C) via “arcs” or “edges” – these are the arrows connecting X to Y etc.
One point for each question.
Q1. Describe what sort of path X2 - C1 – Y is?
Q2. What is U in this DAG?
Q3. What is L in this DAG?
Q4. What is a path describing confounding of X1 and Y?
Q5. What is a path describing mediating of X2 and Y?
Q6. What is a path describing both mediating and confounding of X1 and Y?
Q7. What is an indirect path from X1 to Y?
PART 2. Draw a DAG for your research question (23 points)
Draw a DAG to help explain the causal thinking behind a research question of interest to you. Your DAG should be relevant for data derived from a longitudinal observational study.
over-arching research question: What is the causal effect of child poverty on child development?
Your answer must include responses to the 7 questions in the order below. Strictly no more than 500 words. Do not include references.
1. State your research question (as a question of causal effect) in one sentence (1 points)
2. Describe the implied RCT that you would do if possible, and that this observational study is intended to emulate (3 points)
3. Describe your exposure – be as specific as you can e.g., moderate to intense physical activity for 30 mins duration, 5 times per week (2 points)
4. Describe your outcome – be as specific as you can e.g., systolic blood pressure > 140 mmHg (2 points)
5. Describe confounding of the causal effect and justify from substantive knowledge (5 points)
6. Describe at least one potential mediator of the causal effect, so there is both a direct and indirect effect of the exposure. Justify this from substantive knowledge. Depending on how your DAG is conceptualised, that may mean you also need to consider collider bias (where 2 arrows “collide” into another variable) involving the mediator. (5 points)
7. Present your DAG for the observational study using Daggity (http://www.dagitty.net/) (5 points)