1. Department of Mathematics and Statistics, Boston University , Boston, MA , USA
2. Goergen Institute for Data Science, University of Rochester , Rochester, NY , USA
3. Department of Political Science, Washington University in St. Louis , St. Louis, MO , USA
4. Argyros School of Business and Economics, Chapman University , Orange, CA , USA
5. Department of Mathematics and Statistics, McGill University , Montreal, QC , Canada