Second-generation systematic literature studies using snowballing

Systematic literature studies have become standard practice in software engineering to synthesize evidence in different areas of the discipline. As more such studies are published, there is also a need to extend previously published systematic literature studies to cover new research papers. These first extensions become second-generation systematic literature studies. It has been asserted that snowballing would be a suitable search strategy for these types of second-generation studies, since newer studies ought to refer to previous research on a topic, and in particular to systematic literature studies published in an area. This paper compares using a snowballing search strategy with a published second-generation study using a database search strategy in the area of cross-company vs. within-company effort estimation. It is concluded that the approaches are comparable when it comes to which papers they find, although the snowballing approach is more efficient in this particular case.