53Systematic Literature Reviews
2.5.2 Selection of Primary Studies
The primary studies are selected based on the established inclusion and exclusion criteria.
The selection criteria may be revised during the process of selection, as all the aspects
are not apparent in the planning phase. It is advised that two or more researchers must
explore the studies to determine their relevance.
The process must begin with the removal of obvious irrelevant studies. The titles,
abstracts, or full texts of the collected studies need to be analyzed to identify the primary
studies. In some cases, only the title or abstract may be enough to detect the relevance of the
study, however, in other cases, the full texts need to be obtained to determine the relevance. ...