Studying Firm Growth Distributions with a Large Administrative Employment Database

This paper uses business tax administrative data to describe the annual firm growth rate distribution in Canada over the 2000–2009 period. This administrative tax database provides a unique lense to study firm growth as it allows us to look at the universe of Canadian employer firms and investigate the firm growth distribution across different dimensions. A non-normal, fat-tailed shape for the firm growth distributions holds across years, industries, regions, as well as firm size and age classes. The results show that the distributions of employment growth rates in Canada have more density in both the center and tails than a normal distribution. The evidence paints a picture of firm growth dynamics whereby most firms change very little each year, while a nontrivial amount also markedly grow or decline. A final finding is that young firms, aged four or less, represent a special case with an upwardly skewed distribution and a median growth rate greater than zero.

Non-Gaussian behavior of the internet topological fluctuations

The traditional Gibrat's hypotheses were once used to model the topological fluctuations of Internet. Although it seems to reproduce the scaling relation of Internet's degree distribution, the detailed micro-dynamics have never been empirically validated. Here, we analyze the distribution of degree growth rates of the Internet for various time scales. We find that in contrast to the traditional Gibrat's assumptions, none of the degree growth rates are normally distributed, but behaves as an exponential decrease on its body and a power-law decay on its tail. Moreover, the observed growth rate distribution turns out independent of the initial degree when the time interval enlarges to a year. Our observations do not consist with the traditional Gibrat law model and suggest a more complex fluctuation mechanism underlying the evolution of Internet.