Explanatory model of the diffusion

The model used to analyze the diffusion of ISO 9000 and ISO 14000 is based on the supposition that the growth of certifications of each standard is proportional to the number of existing certifications and that this growth rate is also a function of the number of certifications, both for the general economy as well as for the different economic sectors. In applying this model to the number of ISO 9000 and ISO 14000 certifications existing world-wide up until 2002, we get the parametrized logistic curve. Both series are well explained by the logistic model, since both determination coefficients are greater than 0.99. In addition, the limits that mark a confidence interval of 95%, as well as the moment at which 95% saturation will be achieved. The ISO 9000 saturation point is expected in 2008, whereas the ISO 14000 reaches saturation point two years earlier. Therefore, the newest standard will mature first.. It can also be seen how the number of ISO 9000 certifications seems to stabilize at about 800,000 world-wide, whereas ISO 14000 certifications do so at around 75,000 certificates.

The studies analyzing the motivation for the implementation of these standards emphasize the importance of external factors compared to internal ones. Specifically, empirical studies show that some of the most important external factors concern customer demands, as well as the desire companies have to stand out from the crowd by having the certificate. These factors, along with active promotion by government administration and other bodies that promote the adoption of this type of innovation (business consultants, foundations, associations, etc.), lead to an exponential growth in the number of certificates. However, there comes a time when fewer and fewer companies show any interest in getting certification, because, for example, the perceived competitive advantage of having the certificate diminishes. The economic/financial
analogy seems clear: the value of the certificate is inversely proportional to the number of certificates in
circulation.

After that we adjusted the logistic model to the ISO 14000 certifications in the four countries we decided to analyze (USA, Japan, Spain and UK). In general, we have verified that not only does the model adjust very well, but that different countries are at different stages along the curve, and that the saturation levels in each case are, approximately, 5000 certificates in Spain, 12,500 in Japan, 3,000 in the United Kingdom and 5,500 in the United States.

Finally, in order to get a more detailed answer, it was considered opportune to analyze whether it was possible to adjust the intensity indicators of ISO 14000 certifications to another logistic curve, following the same pattern as before. We analyzed, in particular, how the logistic curve adjusts to a variable constructed as a quotient between the number of certifications and the Gross National Product at constant prices and, in addition, to a quotient of the number of certifications with respect to the number of inhabitants as carried out by Saraiva and Duarte (2003). The adjustment obtained in both cases is also very good, but not as good as the one obtained directly from the number of certifications.