Table 5: Average contribution rate of a potential developer comparing to other members of the project before attaining the role of a developer.

Variable Mean St. dev

Apache Ant (n = 13)
bugs reported 11.15 13.25
bug comments 10.43 8.35
bug social relation 8.42 6.65
emails 19.89 16.25
email social relation 10.97 8.42
Apache Lucene (n = 22)
bugs reported 4.53 3.09
bug comments 4.08 2.89
bug social relation 3.18 1.73
emails 3.91 3.27
email social relation 6.23 4.42
Apache Maven (n = 21)
bugs reported 4.05 3.68
bug comments 2.36 2.01
bug social relation 2.44 1.98
emails 4.05 5.76
email social relation 4.31 3.34
Apache Solr (n = 13)
bugs reported 4.56 5.77
bug comments 4.4 4.72
bug social relation 2.52 2.15
emails 1.05 1.07
email social relation 2.71 1.95