Sampling improvement in software engineering surveys

Context: Small and non-probabilistic samples represent relevant issues when discussing the external validity of empirical studies in Software Engineering. Goal: To investigate alternatives to improve the quality of samples (size, heterogeneity and level of confidence). Method: To replicate a survey on characteristics of agility in software processes by applying a systematic recruitment strategy over a professional social network. Results: It resulted in a sampling frame composed by 19 groups stratified according two perspectives: sharing of groups' members and main software engineering skills reported by the subjects. In total, 7,745 subjects were randomly recruited, resulting in 291 contributions. Conclusions: This sample was significantly larger, more heterogeneous and presents some strata with higher confidence levels than previous trials samples.