Fat tails, long memory, maturity and ageing in open-source software projects

TL;DR

This paper analyzes open-source software project activity, revealing fat-tailed distributions, long memory, cross-correlations, and aging effects, and proposes measures of project maturity based on modification timing.

Contribution

It introduces a novel analysis of activity patterns in open-source projects, linking statistical properties to project maturity and aging phenomena.

Findings

Activity times have fat-tailed distributions and long-term memory.

Project maturity correlates with the exponent of inter-modification times.

File modification rates decay as a power-law over time, indicating aging.

Abstract

We report activity data analysis on several open source software projects, focusing on time between modifications and on the number of files modified at once. Both have fat-tailed distributions, long-term memory, and display systematic non-trivial cross-correlations, suggesting that quiet periods are followed by cascading modifications. In addition the maturity of a software project can be measured from the exponent of the distribution of inter-modification time. Finally, the dynamics of a single file displays ageing, the average rate of modifications decaying as a function of time following a power-law.