The implicative structure of overabundant paradigms

In recent years, both quantitative approaches to the implicative structure of paradigms (Wurzel 1989) and non-canonical properties of paradigms such as overabundance (Thornton 2011) have received growing attention from morphological theory. However, the most prominent framework to quantitatively assess implicative structure, the Paradigm Cell Filling Problem (PCFP, Ackerman et al. 2009), does not consider overabundance. In our paper, we present a strategy to measure paradigm predictability for overabundant paradigms and contrast two fine-grained measures, which we call predictive diversity and prediction reliability. We show that they capture conceptually different properties of paradigms. However, in an empirical study of Estonian nominal declension, we conclude that, once the relative token frequency of overabundant forms is taken into account, the two properties are strongly correlated. Our study confirms that overabundance affects quantitative approaches to the PCFP in non-trivial ways, and that token frequency should not be ignored in this context.