Una possibile generalizzazione dei modelli economici dinamici

The aim of this paper is that of introducing a new class of economic dynamical models, wich we have called «morphogenetic systems»; these latters are been constructed in order to generalize classical Goodwin's model of business cycle. Morphogenetic systems account for the spatial features, besides the temporal ones, of economic dynamics; for this reason they are based on reaction-diffusion partial differential equations. This work results in a formalized definition of these systems; one, thus, can mathematically characterize them in a univocal way.     

The use of imagery in statistical reasoning by university undergraduate students: a preliminary study

Many students have difficulty in grasping several concepts that are related to the solution of statistical problems. The bibliography reports how the ability of students to solve problems can be affected by the mode of the statistical problem presentation: verbal–numerical and pictorial–graphical. The dual-coding theory predicts that the graphical representation mode should enhance students’ statistical reasoning. Solving these problems requires the building, by the subjects, of a mental model, which in turn relies on visuo-spatial processing. To test this hypothesis we analysed how the ability to solve problems of 473 undergraduate students is affected by the mode of the statistical problem presentation. The study used a quasi-experimental mixed design to explore how the student’s performance is related to visuo-spatial and numerical abilities, statistical expertise, time pressure and problem representation mode (verbal/pictorial). Data analysis, based on the Hierarchical Loglinear Model and then the Logit Model, highlighted that the effect of facilitation, induced by the graphical presentation mode, would seem more likely to occur in inexperienced subjects with high visuo-spatial competence.     

Sulla formulazione matematica dei modelli economici di tipo morfogenetico

This paper deals with the mathematical characterizations of economic morphogenetic models, introduced in a previous paper, obtained through a theorem establishing a direct connection between the formalized definition of a morphogenetic system and some inequalities to be satisfed by the coefficients of the variational system associated to an homogenous equilibrium solution. Besides, it is proposed the study of a particular model, giving an explicit proof, to this regard, of the fact that it is a morphogenetic model. This later is examined in order to find its connections with Goodwin's model of economic cycle and the appearance of self-oscillatory behaviour.