In Progress

This section describes my on-going research, with links to unpublished Working Papers. 

Probabilistic choice

This research examines axiomatic foundations for various probabilistic choice models.

I'm working with Jose Rodrigues-Neto and James Taylor on variants of the Luce model.  Here are a couple of working papers on the topic:

    Rodrigues-Neto, RYAN and Taylor (2024) "A Stricter Canon: General Luce Models for Arbitrary Menu Sets"

     Rodrigues-Neto, RYAN and Taylor (2024) "Cycle Conditions for `Luce Rationality'"

We are also working on a paper that examines connections between the modern literature on Luce models and an older literature on conditional probability spaces in game theory.

I am also interested in random utility models.  The following working paper generalises (and somewhat reinterprets) the random categorization rules of Aguiar (Economics Letters, 2017).  A major revision is in (sporadic!) progress:

                    RYAN (2019) "Generalised Random Categorisation Rules"

Ambiguity and the "Jury Paradox"

This work was supported by the Royal Society of New Zealand through the Marsden Fund (16-UOA-190).  The Principal Investigators are my co-authors, Simona Fabrizi and Steffen Lippert at the University of Auckland. 

The Jury Paradox refers to the possibility that raising the voting threshold for conviction (e.g., from simple majority to unanimity) may increase the likelihood of convicting an innocent defendant.  This perverse effect of strategic voting was pointed out by Timothy Feddersen and Wolfgang Pesendorfer (American Political Science Review, 1998).  The purpose of the project is to investigate, both theoretically and experimentally, the impact of ambiguous juror beliefs on the prevalence of this paradoxical phenomenon.

In addition to the 2021 and 2022 papers in Theory and Decision, the following working paper is also part of this project:

                    Fabrizi, Lippert, Pan and RYAN (2024) "Unanimity under Ambiguity"

We are currently preparing additional manuscripts which analyse our experimental data.

Here are the slides from a couple of presentations on the background literature to this topic: Lecture 1 and Lecture 2

And here are slides from a (now somewhat dated) presentation that gives an overview of our research programme.