Grammaticalization has often been described as a gradual phenomenon. While many studies have discussed the quantitative aspects of grammaticalization, there has been little to no work that has tried to propose a way of measuring degrees of grammaticalization. This book addresses this gap by proposing a corpus-based approach to the measurement of grammaticalization, using binary logistic regression modelling.
Such an approach has theoretical benefits as it can provide empirical evidence for the gradience and gradualness of grammaticalization. It can help substantiate observations that have been done on the basis of case studies so far, such as the hypothesized unidirectionality of grammaticalization. In addition, as the methods proposed in this book rely on corpus-based data only, it offers a way of comparing grammaticalization across multiple languages, which is currently a challenging endeavour.
What this book hopes to achieve is to start a discussion on the measurement of grammaticalization. To draw a parallel, the field of morphological productivity has greatly benefited from the discussions (and disputes) regarding how its object of study should be measured, and I believe that so will the field of grammaticalization.