Step 2: Make a Causal Model

Step 2: Make a Causal Model

Farrokh Alemi Ph.D.

This research was funded by Grant RO1 HL 084767 from the National Heart Blood and Lung

Institute.

Step 2: Make a Causal Model

Step 2: Make a Causal Model

This lecture continues from the lecture on making a list of

causes

• Real world relationships• Visual network of causes & effects• Probability distribution

Step 2: Make a Model from Your List

Put Each Cause in a Node

Put the Effect to the Right

Connect Causes to Effect

Put in Constraints

Equivalent Probability Model

Each Node a Function of Nodes Linking to It

Combination of Multiple Causes

p(Exercise | Ready to bike, Ready to shower at gym, Sleep early)= highp(Exercise | Ready to bike, Ready to shower at gym, Slept late)= Between low and high p(Exercise | Ready to bike, No plans to shower at gym, Sleep early)= Between low and high p(Exercise | No plans to bike, Ready to shower at gym, Sleep early)= Between low and high p(Exercise | Ready to bike, No plans to shower at gym, Slept late)= Between low and high p(Exercise | No plans to bike, Ready to shower at gym, Slept late)= Between low and high p(Exercise | No plans to bike, No plans to shower at gym, Slept late)= Low

Out of Sight, Out of Mind

Breakfast time

Probabilistic Dependence

Probabilistic Dependence

biking)Plan |Exercise(Exercise)( pp

Probabilistic Dependence

Probabilistic Dependence

shower) gymPlan |Exercise(Exercise)( pp

Probabilistic Dependence

early) Sleeping|Exercise(Exercise)( pp

• If we knew …• P(A|B) = P(A)

Probabilistic Independence

early) Sleeping|Exercise(Exercise)( pp

Probabilistic Independence

early) Sleeping|shower Plan to(shower) Plan to( pp

Serial Nodes: Root Causes

Rain) bike, Ready to|Exercise(

bike) Ready to|Exercise(

p

p

Multiple Causes

early) Sleeping Exercise,|shower Plan to(

Exercise)|shower Plan to(

p

p

Causa

l model

Probability distribution

Test against data

Probabilities Can Be Tested Against Data

Lecture ContinuesLecture Continues

Step 3: Thought Experiments