Projects Gary Goertz

Necessary conditions in political science

Collaborators: Gary Goertz (editor), Harvey Starr (editor), Bear F. Braumoeller, Claudio Cioffi-Revilla, Douglas Dion, Frank P. Harvey, Jack S. Levy, Alex Mintz, Benjamin A. Most, Charles C. Ragin, George Tsebelis

The edited book Necessary Conditions: Theory, Methodologies and Applications brings together political science researchers discussing necessary conditions. More than hundreds necessary condition hypotheses are identified and different methods to analyse them were explored. The discussion focuses on dichotomous necessary conditions in case based research. Topics include: Conceptualization of the form of relationships, Cause, correlation and necessary conditions, Substantive importance of necessary conditions, Evidence and inference in the comparative case study, Necessary conditions in case studies,  Successes and failures using Boolean Logic and comparative methods, Fuzzy-set analysis of necessary conditions, and statistical methodology of necessary conditions.


Goertz, G., & Starr, H. (Eds.) (2003) Necessary conditions: Theory, methodology, and applications. New York, NY: Rowman & Littlefield.

Ceilings and floors: where are there no observations?

Collaborators: Gary Goertz,  Tony Hak, and Jan Dul

There are situations where the data or the theory suggest or require, respectively, that one estimate the boundary lines that separate regions of observations from regions of no observations. Of particular interest are ceiling or floor lines. For example, many theories use terms such as veto player, constraint, only if, and so on, which suggest ceilings. Ceiling hypotheses have a nonstandard form claiming the probability of Y will be zero for all values of Y greater than the ceiling value of Yc for a given value of X. Conversely, ceiling hypotheses make no specific prediction about the value of Y for a given value of X except that it will be less than the ceiling value. Floors work by guaranteeing minimum levels. The article gives numerous examples of theories that imply ceiling or floor hypotheses and numerous examples of data that fit such hypotheses. The article proposes quantile regression as a means of estimating the boundaries of the no-data zone as well as criteria for evaluating the importance of the boundary variable. These techniques are illustrated for ceiling and floor hypotheses relating gross domestic product/capita and democracy.


Goertz, G., Hak, T., and Dul, J. (2008). Ceilings and floors: theoretical and statistical considerations when the goal is to draw boundaries of data, not lines through the middle. Proceedings of the 2008 American Political Science Association Annual Meeting, Boston, Massachusetts, USA, August 28-31, 2008.

Goertz, G., Hak, T., and Dul, J. (2013). Ceilings and floors where are there no observations? Sociological Methods & Research, 42 (1), 3-40.

Necessary condition hypotheses in operations management

Collaborators:  Jan Dul,  Tony Hak,, Gary Goertz, and Chris Voss

The purpose of this paper is to show that necessary condition hypotheses are important in operations management (OM), and to present a consistent methodology for building and testing them. Necessary condition hypotheses (“X is necessary for Y”) express conditions that must be present in order to have a desired outcome (e.g. “success”), and to prevent guaranteed failure. These hypotheses differ fundamentally from the common co-variational hypotheses (“more X results in more Y”) and require another methodology for building and testing them. The paper reviews OM literature for versions of necessary condition hypotheses and combines previous theoretical and methodological work into a comprehensive and consistent methodology for building and testing such hypotheses. Necessary condition statements are common in OM, but current formulations are not precise, and methods used for building and testing them are not always adequate. The paper outlines the methodology of necessary condition analysis consisting of two stepwise methodological approaches, one for building and one for testing necessary conditions. Because necessary condition statements are common in OM, using methodologies that can build and test such hypotheses contributes to the advancement of OM research and theory.


Dul, J., Hak, T., Goertz, G., & Voss, C. (2010). Necessary condition hypotheses in operations management. International Journal of Operations & Production Management, 30, 1170–1190.