Open Collections

Hartford, Jason Siyanda

University of British Columbia

To design good policy, we need accurate models of how the decision makers that operate within a given system will respond to policy changes. For example, an economist reasoning about the design of an auction needs a model of human behavior in order to predict how changes to the auction design will be reflected in outcomes; or a doctor deciding on treatments needs a model of people's health responses under different treatments to select the best treatment policy. We would like to leverage the accuracy of modern deep learning approaches to estimate these models, but this setting brings two non-standard challenges. First, decision problems often involve reasoning over sets of items, so we need deep networks that reflect this structure. The first part of this thesis develops a deep network layer that reflects this structural assumption, and shows that the resulting layer is maximally expressive among parameter tying schemes. We then evaluate deep network architectures composed of these layers on a variety of decision problems from human decision making in a game theory setting, to algorithmic decision making on propositional satisfiability problems. The second challenge is that predicting the effect of policy changes involves reasoning about shifts in distribution: any policy change will, by definition, change the conditions under which decision makers operate. This violates the standard machine learning assumption that models will be evaluated under the same conditions as those under which they were trained (the ``independent and identically distributed'' data assumption). The second part of this thesis shows how we can train deep networks that make valid predictions of the results of such policy interventions, by adapting the classical causal inference method of instrumental variables. Finally, we develop methods that are robust to some violations of the instrumental variable assumptions in settings with multiple instrumental variables.

Text

2021-05-12

Attribution-NonCommercial-ShareAlike 4.0 International

http://hdl.handle.net/2429/78301

Computer Science

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-sa/4.0/