A site with very popular content, which appears in 1999, will soon have more links than a bland site created in 1993. It is likely that the rate of acquisition of new links is proportional to the number of links the site has already. After all, the more links a site has, the more visible it becomes, the more new links it will get. However, there should be an additional proportionality factor, or growth rate, which varies from site to site. In this model, at each time step the number of new links a site receives is a random fraction of the number of links the site already has.
New sites appear at an exponential rate and each has a different growth rate.
2 Scatter plot of the number of links, k , vs. age for 120,000 sites. The correlation coefficient is 0.03.