The Narrative Literature Review is qualitative in nature; it provides a conceptual overview of previous research. The review is structured and can be organized by themes, chronological method, or by methodological approach. It assesses the strengths and weakness of previous research and finishes with a conclusion on the research topic. A narrative literature does not include any detail on the literature reviewed such as research design or information on search procedures.
Systematic Reviews can be qualitative or quantitative; its purpose is to provide a synthesis of pre-selected literature on a given topic. The process of systematically selecting the literature is done to limit any bias or random error. Systematic reviews evaluated in depth the quality of each selected study and its research methodology; it also discusses the search procedure of conducting the review.
Meta-analysis is a systematic review which analyzes and summarizes quantitative research studies on a topic. It combines the statistical results from exhaustive amount of studies to produce an overall summary of the literature.
The Systematic Review-- the "Gold Standard" of Evidence