Table 4: Yearly average contribution ratio of a potential developer before and after attaining the role of a developer.

Variable Mean St. Dev
Before After Before After

Apache Ant (n = 13)
bugs reported 17.23 2.35 17.98 3.65
bug comments 41.44 39.02 37.66 34.83
bug social relation 44.65 31.57 51.41 23.34
emails 230.49 280.34 259 224.52
email social relation 30.5 20.31 30.35 13.55

Apache Lucene (n = 22)
bugs reported 14.12 23.73 9.12 32.74
bug comments 24.84 73.21 18.18 91.85
bug social relation 33.57 34.67 23.75 30.02
emails 130 398.71 124.87 508.02
email social relation 19.59 21.69 16.53 15.32

Apache Maven (n = 21)
bugs reported 28.40 27.82 53.27 79.49
bug comments 16.42 27.86 12.07 58.68
bug social relation 27.16 24.08 21.43 30.85
emails 158.41 185.55 218.27 174.89
email social relation 18.33 23.34 18.31 15.73

Apache Solr (n = 13)
bugs reported 24.77 23.75 30.38 17.50
bug comments 44.72 84.77 41.35 86.25
bug social relation 68.04 80.46 52.18 52.39
emails 156.01 313.82 227.57 333.19
email social relation 14.72 38.47 7.85 33.04