The evolution of FreeBSD and linux

Is the nature of Open Source Software (OSS) evolution fundamentally different from that of the traditional and commercially available software systems? Lehman and others conducted a series of empirical studies that found that traditional systems grow at a linear or sub-linear rate. A prior case study of the Linux OSS system suggests that OSS may evolve in a unique manner. Godfrey and Tu found that some aspects of Linux are growing at a super-linear rate rather than a sub-linear rate. Additional studies are necessary before drawing conclusions. Thus, we examine the evolution of FreeBSD and re-analyze the evolution of Linux, and find evidence that the growth of both systems has a linear upper bound, and thus appear to grow at similar rates to that of commercial systems. These results do not support the hypothesis that OSS systems grow at rates that exceed that of traditional systems.