Skip to main content

Modeling-Related Processes With an Excess of Zeros

  • David Carlson

Political science research frequently models binary or ordered outcomes involving related processes. However, traditional modeling of these outcomes ignores common data issues and cannot capture nuances. There is often an excess of zeros, the observed outcomes for different actors are inherently related, and competing actors may respond to the same factors differently. This paper extends existing models and develops a zero-inflated multivariate ordered probit to simultaneously address these issues. This model performs better than existing models at capturing the true parameters of interest, estimates the nature of the related processes, and captures the differences in actors’ decision-making. I demonstrate these benefits through simulation exercises and an application to party behavior in Mexico.

Hide All

Department of Political Science, Washington University in Saint Louis, Campus Box 1063, 1 Brookings Drive, Saint Louis, MI 63130-4899 ( The author would like to sincerely thank Siddhartha Chib, Jeff Gill, Jacob M. Montgomery, Guillermo Rosas, Margit Tavits, Michelle Torres, every member of the Comparative Politics Workshop and of the Data Science Lab of Washington University in St. Louis for their invaluable comments. To view supplementary material for this article, please visit

Hide All
Albert, James H., and Chib, Siddhartha. 1993. ‘Bayesian Analysis of Binary and Polychotomous Response Data’. Journal of the American Statistical Association 88(422):669679.
Bagozzi, Benjamin E., Hill, Daniel W., Moore, Will H., and Mukherjee, Bumba. 2015. ‘Modeling Two Types of Peace: The Zero-Inflated Ordered Probit (Ziop) Model in Conflict Research’. Journal of Conflict Resolution 59(4):728752.
Bagozzi, Benjamin E., and Marchetti, Kathleen. 2014. Distinguishing Occasional Abstention from Routine Indifference in Models of Vote Choice. Political Science Research and Methods 5(2):277–294.
Cameron, Colin, and Trivedi, Pravin K.. 2005. Microeconometrics: Methods and Applications. New York, NY: Cambridge University Press.
Dunne, John Paul, and Tian, Nan. n.d. The Determinants of Civil War and Excess Zeros. Working Paper, University of Cape Town, Cape Town.
Gurmu, Shifrew, and Dagne, Gatachew A.. 2012. Bayesian Approach to Zero-Inflated Bivariate Ordered Probit Regression Model, With an Application to Tobacco Use. Journal of Probability and Statistics 2012:26, Article ID 617678.
Harris, Mark N., and Zhao, Xueyan. 2007. ‘A Zero-Inflated Ordered Probit Model, With an Application to Modelling Tobacco Consumption’. Journal of Econometrics 141(2):10731099.
Kadel, Rajendra. 2013. ‘A Latent Mixture Approach to Modeling Zero-Inflated Bivariate Ordinal Data’. PhD Thesis, University of South Florida, Tampa, FL.
King, Gary. 1989. ‘A Seemingly Unrelated Poisson Regression Model’. Sociological Methods & Research 17(3):235255.
King, Gary, and Zeng, Langche. 2001a. ‘Explaining Rare Events in International Relations’. International Organization 55(3):693715.
King, Gary, and Zeng, Langche. 2001b. ‘Logistic Regression in Rare Events Data’. Political Analysis 9(2):137163.
Langston, Joy, and Rosas, Guillermo. 2016. Presidential Campaigns Under Single-District Plurality: Visits, Rallies, and the Calculus of Electoral Mobilization in Mexico. Submitted.
Laslier, Jean-F., and Picard, Nathalie. 2002. ‘Distributive Politics and Electoral Competition’. Journal of Economic Theory 103(1):106130.
Nieman, M. D. 2015. Statistical Analysis of Strategic Interaction With Unobserved Player Actions: Introducing a Strategic Probit With Partial Observability. Political Analysis 23(3):429–48.
Zellner, Arnold 1962. ‘An Efficient Method of Estimating Seemingly Unrelated Regressions and Tests for Aggregation Bias’. Journal of the American statistical Association 57(298):348368.
Zellner, Arnold, and Huang, David S. 1962. ‘Further Properties of Efficient Estimators for Seemingly Unrelated Regression Equations’. International Economic Review 3(3):300313.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Political Science Research and Methods
  • ISSN: 2049-8470
  • EISSN: 2049-8489
  • URL: /core/journals/political-science-research-and-methods
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
Type Description Title
Supplementary materials

Carlson supplementary material
Carlson supplementary material 1

 PDF (91 KB)
91 KB


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed