Advanced level · Module 1: Causal Inference and Programme Evaluation · Lesson 1 of 4
Thinking Causally
Frame causal questions with counterfactuals and draw causal diagrams to reveal confounders.
In this lesson you will
- Define a causal effect using counterfactuals
- Draw a causal diagram and identify confounders to adjust for
Key concepts
counterfactualcausal effectdirected acyclic graphconfounder vs mediator
The lesson
A causal effect compares what happened with what would have happened without the intervention — the counterfactual, which can never be observed for the same people. Evaluation designs construct a credible comparison.
A causal diagram (DAG) draws arrows from causes to effects. It shows which variables are confounders (adjust for them), which are mediators on the causal path (do not adjust if you want the total effect) and which create bias if adjusted for.
Diagrams make assumptions explicit, so colleagues and programme staff can challenge them.
Step by step
- Write the counterfactual question for a feeding programme.
- Draw a causal diagram with five variables.
- Mark confounders and mediators.
- Decide which to adjust for.
Practice activity
Draw and explain the causal diagram for the feeding programme evaluation.
Expected result: A diagram with justified adjustment choices.
Check your understanding
-
What is a counterfactual?
Show answer
What would have happened without the intervention.
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Should you adjust for a mediator when estimating a total effect?
Show answer
No; it is part of the effect's pathway.
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