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Grupo de Estudos Monetários e Financeiros

Estudos do GEMF, N.º 20 de 2011


Fitting Broadband Diffusion by Cable Modem in Portugal

Rui Pascoal
Faculdade de Economia, Universidade de Coimbra

Jorge Marques
Faculdade de Economia, Universidade de Coimbra

The purpose of this article is to describe the evolution of the number of residential subscribers of broadband fixed access by cable modem, in Portugal, on the period from 2000–2009. The pattern of evolution is estimated by fitting several models to the series, namely the following: exponential, Gompertz, Logistic, Bass and Michaelis-Menten. We fit the models to the data by nonlinear least squares, except in the exponential model where the linear version is fitted by ordinary least squares, using the internet freely available program R. This comparative study is in line with many others on the diffusion of technological innovations in the telecommunications sector, where the point is finding out if there is an early or a late take-off phenomenon. The Michaelis-Menten model is introduced for the first time in this approach. It allows to predict the later evolution in the series and reveals a qualitatively different behavior.

JEL Classification: C02, C53, L96, 033.

Broadband, Technological Innovations, Diffusion Growth Models, Nonlinear Least Squares.

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