We performed a systematic literature review using the three databases Scopus, ACM Digital Library, and IEEE Xplore. Comment from one reviewer was that Scopus contains the other two databases, and thus searching ACM and IEEE is redundant. Our results do not indicate that Scopus covers the two databases.
Question: Does Scopus cover the ACM Digital Library and IEEE Xplore databases?
The empirical search results suggest that it is not sufficient to search in Scopus and get all results from ACM and IEEE also in Scopus. However, there are at least two things that could be partially responsible for the empirical results not always helping here: (a) The time lag in updating the indexes (when and how often are the ACM and IEEE databases integrated into the Scopus database?) and the search methodology (in ACM, full text is apparently searched by default (instead of abstract, title and keywords), we got more articles in ACM than in Scopus, but could not attribute this to the search methodology. However, we cannot exclude errors on our part here.
Furthermore, there are systematic literature reviews in well-ranked journals that search all three databases, among others, e.g.: Johnson, D., Deterding, S., Kuhn, K.-A., Staneva, A., Stoyanov, S., & Hides, L. (2016). Gamification for health and wellbeing: A systematic review of the literature. Internet Interventions, 6, 89–106.
Our search for "official information" found the Scopus Content Coverage Guide 1. Here IEEE is mentioned as indexed, ACM does not appear, but there is a rather large "Other" block of 60%.