GoogleScholar vs. SSCI

vs.

Searching literature and identifying the relevant papers for your academic work is - in my eyes - one of the most time-consuming and sometimes annoying activities. Databases that do not feature sorting in terms of "relevance" may be helpful for very specific searches, but are quite useless when you want an overview of a large field. A good alternative are always literature reviews, however - you need to find one and most importantly: it has to be your topic.
Most social scientists rely heavily on Thomson's SSCI. Over the last few years Google Scholar has emerged as a potential rival or at least a supplement to SSCI-based approaches. Apart from being free - which is important as not all universities and certainly no laymen can afford the SSCI access - Google Scholar has some other advantages over the SSCI, but there are drawbacks as well. Finding recent working papers and also several versions of published papers is a great advantage in my eyes. As Google Scholar works somewhat non-systematic, one might have doubts about the overall coverage and about the reliability of the citation numbers and its relevance sorting. Walters (2007) addresses these issues and provides an interesting benchmark of Google Scholar, the SSCI and some other databases using the field of later-life migration:

Because Google Scholar’s search, retrieval, and record management mechanisms are relatively unsophisticated, the current version of GS is unlikely to replace conventional social science databases for serious scholarly work. Google Scholar is nonetheless valuable due to its comprehensive coverage. Within the field of later-life migration, GS indexes 27% more core articles than the second-ranked database (SSCI) and 2.4 times as many core articles as the lowest-ranked database (GEOBASE). Moreover, it covers 88–100% of the core articles found in each of the other seven databases. read more...

While I always had doubts about using Google Scholar when searching literature, this sounds like a good legitimization for using it. For quantification however I would still stick with the SSCI - merely as it is the quasi-standard for citation data.

Philipp Mayr and Anne-Kathrin Walter of GESIS (German Social Science Infrastructure Services) offer another benchmark: in a (german-language) paper and a presentation.