Η διατριβή εξετάζει το ρόλο της παραγωγικής αποτελεσματικότητας ως μιας σύνθετης μεταβλητής (τεχνική αποτελεσματικότητα και αποτελεσματικότητα κλίμακας) που αποτυπώνει τη συμπεριφορά των επιχειρήσεων ενός κλάδου.σε επίπεδο διακλαδικής ανάλυσης εξετάζεται ο ρόλος της παραγωγικής αποτελεσματικότητας ως μεταβλητή η οποία αποτυπώνει στρατηγικά διαμορφωμένα εμπόδια εισόδου στους ενεργειοβόρους κλάδους της ελληνικής βιομηχανίας. σε επίπεδο ενδοκλαδικής ανάλυσης εξετάζεται ρόλος της παραγωγικής αποτελεσματικότητας ως μεταβλητή η οποία επηρεάζει την πιθανότητα εισόδου νέων επιχειρήσεων σε ένα κλάδο και την πιθανότητα εξόδου υπαρχόντων επιχειρήσεων απο ένα κλάδο. / It analyses the role of multifaceted productive efficiency (technical and scale efficiency)as a variable that captures the conduct of firms in an industry. at the interindustry level of analysis productive efficiency is analysed as a variable that captures strategic entry barriers in the greek energy intensive manufacturing industries. at the intraindustry level of analysis productive efficiency is analysed as a variable that affects the probability of new firms entering an industry and the probability of existing firms exiting the industry.

Questo lavoro studia la distribuzione della dimensione d'impresa sulla base di due datasets. Il primo è l'indagine micro1 di istat, che include tutte le imprese manifatturiere con più di 20 addetti sopravvissute dal 1989 al 1997. Il secondo è il file Cerved riguardante l'universo delle imprese del settore meccanico (atecodk29), dal 1997 al 2002. Lo scopo generale della tesi è quello di espolare la possibilità di trovare nuove regolarità empiriche riguardanti la distribuzione della dimensione d'impresa, sulla base della passata evidenza empirica che attesta la (in)capacità di Lognormale e Pareto di modellare in modo soddisfacente la dimensione d'impresa nell'intero arco dimensionale. Vengono per questo proposti due modelli mai utilizzati prima. Gli stessi vengono poi convalidati su differenti variabili dimensionali e a diversi livelli di aggregazione. La tesi cerca anche di esplicitare al meglio le implicazioni economiche dei modelli parametrici di distribuzione adottati secondo diversi punti di vista. / The present work studies the firm size distribution of Italian manufacturing industries on the basis of two datasets. The first is the Micro1 survey carried out by ISTAT, which recorded all manufacturing firms with 20 employees and more surviving from 1989 to 1997. The second is the Cerved file regarding all firms of the mechanical sector (DK29) from 1997 to 2002. The general aim of this research is to explore the possibility to find new empirical regularities in the size distribution of firms, building on the relevant past evidence about the (in) capacity of the Lognormal and Pareto distribution of satisfactorily modelling the whole size range. Two unused statistical models are proposed and validated on different size proxies and at different levels of data aggregation. The thesis also addresses the economic implications of parametric models of firm size distribution in different aspects.