Systematic literature reviews (SLRs) are a major tool for supporting evidence-based software engineering. Adapting the procedures involved in such a review to meet the needs of software engineering and its literature remains an ongoing process. As part of this process of refinement, we undertook two case studies which aimed 1) to compare the use of targeted manual searches with broad automated searches and 2) to compare different methods of reaching a consensus on quality. For Case 1, we compared a tertiary study of systematic literature reviews published between January 1, 2004 and June 30, 2007 which used a manual search of selected journals and conferences and a replication of that study based on a broad automated search. We found that broad automated searches find more studies than manual restricted searches, but they may be of poor quality. Researchers undertaking SLRs may be justified in using targeted manual searches if they intend to omit low quality papers, or they are assessing research trends in research methodologies. For Case 2, we analyzed the process used to evaluate the quality of SLRs. We conclude that if quality evaluation of primary studies is a critical component of a specific SLR, assessments should be based on three independent evaluators incorporating at least two rounds of discussion.

This study aims to compare the use of targeted manual searches with broad automated searches, and to assess the importance of grey literature and breadth of search on the outcomes of SLRs. We used a participant-observer multi-case embedded case study. Our two cases were a tertiary study of systematic literature reviews published between January 2004 and June 2007 based on a manual search of selected journals and conferences and a replication of that study based on a broad automated search. Broad searches find more papers than restricted searches, but the papers may be of poor quality. Researchers undertaking SLRs may be justified in using targeted manual searches if they intend to omit low quality papers; if publication bias is not an issue; or if they are assessing research trends in research methodologies.

Context: Although the Unified Modeling Language (UML) is now widely used, there is little empirical knowledge about the effectiveness of its different elements. Objectives: To conduct a systematic review of the literature describing empirical studies of this paradigm. Method: We undertook a Mapping Study of the literature, based upon electronic searching of major digital libraries. Results: 33 papers have been identified and classified by topic, form of study involved, and type of publication. Conclusions: The largest group of empirical studies of the UML concentrate on comprehension, and many key aspects have hardly been investigated at all.