Probabilistic Model of Logistic Regressions

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2.4 Probabilistic Model of Logistic Regressions

Probabilistic model of regression model makes use of corpus data as the basis analysis and then combined the result of analysis with regression model in SPSS. The result of the variables in the equation in SPSS then is computed with the logit probabilistic formula of logistic regression. The method of dynamic probabilistic grammar has been used in several prior studies Bybee Hooper 2001; Bod et al. 2003; Gahl Garnsey 2006; Gahl Yu 2006. But then, Bresnan 2007 focuses the use of this dynamic probabilistic grammar to the domain of syntactic variation. The focus of probabilistic model in syntactic variation is to predict the occurrences of certain construction. When the probabilistic value gets closer to one, the tendency for the event to happen is high. Conversely, when the probabilistic value is closer to zero the tendency for the event to happen is low. Below is the logit formula of probabilistic binary logistic regression model Sunyoto 2007; Suharjo 2008 : constant+ β1 x1+ β2 x2+ β3 x3+… + βn xn e In p constant+ β1 x1+ β2 x2+ β3 x3+… + βn xn 1+e expconstant+ β1 x1+ β2 x2+ β3 x3+… + βn xn 1+ expconstant+ β1 x1+ β2 x2+ β3 x3+… + βn xn In p = constant+ β1 x1+ β2 x2+ β3 x3+… + βn xn 1 - p Where p represents the probability of the event to happen, in this case benefactive PP or double object construction. β is the coefficient of each linguistic features. β1 30 represents the coefficient of feature 1, β2 represents the coefficient of feature 2, and so forth. When the constant and coefficients were obtained from the mixed-effect binary logistic, the formula above can be completed and was able to predict the occurrence of certain grammatical alternation, in this research casebenefactive construction. The probabilistic formula gives us the percentage of certain instance to take benefactive PP or double object construction. In addition, from the computed data in the regression models, the research could obtain the model fit accuracy of the corpus probabilistic formula of benefactive construction.

2.5 Related Studies