Literature reviews are summaries of the literature on a particular topic. Reviews are generally considered "research", especially systematic and integrative reviews, but are not experimental in nature. There are several kinds of reviews: plain literature reviews, systematic reviews, and integrative reviews are the most common. Chapter 5 of Introduction to Nursing Research: Incorporating Evidence-based Practice (Cannon & Boswell, 2011) covers the purpose and process of a literature review in the context of writing a research article, thesis, or dissertation.
Types of literature reviews:
*A meta-analysis study is one where carefully selected data from previous studies is combined to bring more rigor to a statistical or other analysis. No additional experimental work is done (usually). A systematic review is necessary to be sure that the data from the selected studies is comparable and combinable.