# Cyclic causal models

The on-going Master's thesis project

For my thesis, I’ve been working on causal modeling, especially concerning the *directed cyclic graph* (DCG) models under the supervision of Dr. Oisín Ryan. In many practical cases, cylces or feedback loops are present, but there are only limited tools available for estimating cyclic causal models, while directed acyclic graph (DAG) has become popular and studied extensively. Furthermore, the cyclic causal discovery methods that have been developed are rather complex and hence difficult to apply.

Therefore, the main motivations for this project is to provide an accessible overview of cyclic causal discovery methods and to investigate the applicability of these methods in empirical research.

In this project, I focus on *constraint-based* cyclic causal discovery methods, which aim to construct the underlying causal structure using statistical independence relations.

We consider three algorithms: CCD, FCI, and CCI. In principle, they all work in a very similar way, but each of them relies on a different set of assumption, as shown below in the table.

To investigate the performance of these algorithms, we conduct a simulation study. The siumulation design is as follows.

We are currently running the simulations. Stay tuned for an update!