| Type of Document |
Dissertation |
| Author |
Dash, Denver
|
| Author's Email Address |
ddash@sis.pitt.edu |
| URN |
etd-05072003-102145 |
| Title |
Caveats for Causal Reasoning with Equilibrium Models |
| Degree |
Doctor of Philosophy |
| Program |
Intelligent Systems |
| School |
School of Arts and Sciences |
| Advisory Committee |
| Advisor Name |
Title |
| Marek Druzdzel |
Committee Chair |
| Greg Cooper |
Committee Member |
| Milos Hauskrecht |
Committee Member |
| Richard Scheines |
Committee Member |
| Vanathi Gopalakrishnan |
Committee Member |
|
| Keywords |
- causality
- dynamics
- Bayesian networks
- structural equation models
- feedback
- Do operator
|
| Date of Defense |
2003-03-18 |
| Availability |
unrestricted |
Abstract
This thesis raises objections to the use of causal reasoning with equilibrium models. I consider two operators that are used to transform models: the {em Do} operator for modeling manipulation and the {em Equilibration} operator for modeling a system that has achieved equilibrium. I introduce a property of a causal model called the {em EMC Property} that is true iff the {em Do} operator commutes with the {em Equilibration} operator. I prove that not all models obey the EMC property, and I demonstrate empirically that when inferring a causal model from data, the learned model will not support causal reasoning if the EMC property is not obeyed. I find sufficient conditions for models to violate and not to violate the EMC property. In addition, I show that there exists a class of models that violate EMC and possess a set of variables whose manipulation will cause an instability in the system. All dynamic models in this class possess feedback, although I do not prove that feedback is a necessary or a sufficient condition for EMC violation. I define the {em Structural Stability Principle} which provides a necessary graphical criterion for stability in causal models. I will argue that the models in this class are quite common given typical assumptions about causal relations.
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| Files |
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Approximate Download Time
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56K Modem |
ISDN (64 Kb) |
ISDN (128 Kb) |
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Dash_April2003.pdf |
1.28 Mb |
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