The literature review of a dissertation has three main purposes. The first is to demonstrate knowledge of the foundational theories and models. The second is to demonstrate appropriate understanding of the current state of the body of knowledge in your field. The third is to provide support within the historical literature for your proposed design. Finally, your literature review will need to definitely indicate that scholars recently indicated a need for your study, or, as I like to say, that the needle does not exist in the haystack.
The review of the literature should not read like a series of book reports. Rather, you will organize the review around five to seven themes that emerge from the literature. The one section within Chapter 2 will need to be a minimum of 30 pages covering a minimum of 50 unique sources. You can have more themes and sources, but you will not want fewer. The review of the literature demonstrates to the reader that you understand the body of knowledge, that you have read it comprehensively, and know the current thinking on your topic. You cannot simply discuss the sources that support your presumed or hypothesized outcome but will need to discuss all sides of the discovered arguments or positions.
Your review of the literature must focus on the recent body of knowledge; 85% of your sources in the review of the literature section may need to have been published within five years of when the dean signs your completed dissertation. If you plan to finish in 2024, for example, only 15% of your sources in the section can be published before 2020. Older sources should be reserved for the Background to the Study and the Theoretical Foundation discussions. Note that the 85% rule does not apply to the entire proposal or dissertation, but only to the one section in Chapter 2.
Note that the majority of your sources will need to be articles from peer-reviewed, academic sources. The university will limit you to no more than five dissertations and five books; your chair may reduce that number, but not increase it. You will not be able to use books or dissertations to substantiate your problem space. You should also resist the temptation to be overly liberal or expansive in your generalization of the context for published studies to fit your selected context; you should not, for example, use a study from outside the United States to substantiate a study inside the United States or a study of turnover among nurses to substantiate a study of turnover among community college faculty.
Your literature review will be organized around five to seven themes. While you may select the themes on your own, the themes will usually emerge logically from your review of the literature. It is important, then, to organize your notes to capture the themes identified by others. You should also capture the design elements of the studies you review and the foundations selected by the authors. What assumptions and limitations did they identify? How did they select their sample? What population did they select? How did they collect their data?
The literature review logically leads to your identification of the problem space and also to your design of your study. How will you get a sense of what the primary themes related to your dissertation are and who the foundational theorists and what the foundational models are?
Considered actually mapping out your dissertation. In mapping the dissertation, like an outline, consider how the headings flow together and how the sub-themes connect to your main themes and everything connects to the problem statement. As you think about themes and sub-themes, an important element of writing, especially Chapter 2, is to create appropriate transitions from the end of one section to the beginning of the next. Effectively, you use the conclusion of the discussion of one theme or sub-theme to transition to the next theme or sub-theme and use the introduction of that next theme or sub-theme to continue the transition.
How do you know when to stop? The literature review is not your opportunity to publish for the world to read everything you know about everything. However, a solid, but not rambling, review of the literature can be 50 or more pages. The review, like the rest of the dissertation should reflect synthesis, not summary.
If synthesizing the literature takes time and practice, or skill, when should a doctoral learner begin practicing that skill? How do you synthesize if your knowledge of the topic is limited? When do you feel comfortable enough with your knowledge of the topic to synthesize? What do you do in the interim? Why would synthesis lead to new concepts?
Most dissertations will have at least 50 sources and perhaps as many as 100. At least 43 sources need to have been published within five years of your expected dissertation defense. How many sources is not really the question, but rather how many do you need to demonstrate that you understand the current body of knowledge regarding your topic, the historical development of your topic and its foundational theories and models, and the methods, designs, and instruments used by scholars looking at topics related to yours. As with many of the research designs you will explore, you keep reading until you are reading nothing new or until your chair tells you to stop.
It is critical that you write at a doctoral level if you want to finish the degree in something close to three years. It is also critical that you have read 100 articles related to your topic before you start writing your prospectus. Knowing APA will help considerably, but not as much as knowing the literature related to your topic. Where you will really notice a difference is if you both know APA and doctoral writing, you can save yourself considerable time and money for editors. An editor might take a week or two each time you ask them to review your document and might charge you a few hundred dollars each iteration.
An abundance of research, as with a dearth of research, can be both good news and bad news. On the one hand, you have a large volume of material to process, and may get some specific guidance as to the gap. On the other hand, you may find that the gap you believe exists in the literature does not actually exist. On the flip side, a dearth of research means that the topic is wide open but may also mean that nobody has actually asserted that a gap exists in the literature but may also mean that nobody has expressed any interest in your proposed topic.
Consider this process map for a literature review: Developing the Literature Review