The Introduction

When writing the literature review, you will generally start with the introduction. The goals of the introduction are to:

• identify the research context
• point out a gap in current understanding
• address why resolving the gap is important
• set the foundation for how a proposed study would address/close the gap in the knowledge 

Research is very often justified by an existing gap in the literature and identifying why it is important to fill the gap. While identifying a gap in the literature is generally viewed as one of the primary reasons for writing a literature review (and subsequently conducting research), there are a variety of ways to identify the gaps.

Are there methodological flaws?

One way to identify a gap in the literature is to point out methodological flaws in the empirical research. Methodological flaws broadly refer to the ways that the study was carried out, including how participants were recruited, selected, and assigned. Methodological flaws are not uncommon in research and are often easy to spot with a critical eye.

Are there existing disagreements?

Another way to identify a gap in the literature is to pinpoint a disagreement between a theory and empirical research.  A theory refers to a set of principles or statements that attempts to explain how variables might be related to one another.  However, empirical findings aren’t always consistent with theorized relationships.  A theory might suggest, for example, that impoverished people are more likely to commit crimes, while the empirical research might reveal that individuals living in poverty situations are at no greater risk than more affluent individuals for engaging in criminal behavior. 

A third way would be to highlight a disagreement between competing theories. No theory can sufficiently and adequately explain all of the complexities of human behavior (at least I have yet to encounter that theory!), so it is very likely that you will come across multiple theories that are at odds with one another in their attempt to explain some aspect of human behavior.

Is the existing research lacking?

And lastly, if there is either inadequacy or an absence of research on a particular subject. Even though this is a possibility, you will probably not come across a topic that no one has investigated yet (science has a way of humbling us that way). However, you could come across a topic that has received very little attention, and in that case, the paucity of work in that area would be an appropriate justification for your research.