Literature reviews: functions, types and methods
From Marshall Dozier on October 7th, 2019
When we think of a literature review, we often forget to consider the different types of reviews and the different roles or functions that literature reviews can have.
In this short presentation I will first discuss some functions of literature reviews, and then make some points about how the function or purpose of your review should inform the type that you choose to do, and the methods that you employ.
Firstly, studying prior literature is instrumental in creating a research agenda.
To start with, let’s take the systematic review, which I’ve put in the extreme corner of Narrow and Formulaic. By narrow, I mean that in general systematic reviews have a very focused and specific research question. By formulaic, I mean that systematic reviews follow a pre-established formula: a protocol is developed in advance of the review proper, and in theory, a different team working on the review and following the same methods should arrive at the same conclusions. The systematic review is generally meant to be reproducible. This approach is based in the positivist tradition usually associated with sciences and biomedicine, and I’d say this approach is like treating the data from literature like the materials in a laboratory protocol.
Next, let’s look to the left at the historical or narrative literature review, which I’ve characterised as Purposive and not as narrow as a systematic review. A traditional literature review that has the aim of summarising developments in an area is usually of great value as an introduction for people new to the topic. I think of these types of reviews as analogous to a lecture or keynote speech. The author selects prior work as illustrative of trends, ideas or controversies and guides the reader through past, present and potential future developments. This is what I mean by Purposive: selective and illustrative, to focus on chosen points. Two experts in the area may select different prior works as illustrations, and may highlight with different emphasis different trends, ideas or areas of contention. Reproducibility in a lecture or a keynote speech is not an objective, and disagreements may well exist. Gaining an understanding of the bases for disagreements is an important aspect of reading around reviews and following up on the sources identified in these reviews.
Next, scoping reviews. I’ve placed these fairly centrally between purposive and formulaic, though there are many scoping reviews that adopt quite systematic methods – so that marker could well be further to right and might be more accurately presented as a line rather than a dot. One feature of scoping reviews in comparison to systematic reviews is that they tend not to address a very narrow question from the outset; rather they are – or at least start as – a broad exploration of work in an area with the aim of describing what’s been done. For example, in a topic area, what particular issues have been researched? With what methods and under what constraints? This exploratory and descriptive mapping of prior work in an area can be a first stage for a more focused and narrowly-defined systematic review. Scoping reviews may be formulaic but they are not always so. In comparison with historical reviews, scoping reviews tend to take a more comprehensive approach in surveying and describing the literature.
Finally, in the upper left hand area, I’ve placed the typical literature review chapter in a dissertation or thesis. This chapter is doing much of the various work described in functions that came up in the centre for medical education seminars: it has a function to contextualise the dissertation in prior work, to present the reader with theoretical approaches that have a bearing on the research being presented, to provide definitions, to delimit gaps in prior work – the various functions that will equip your reader to understand the study presented in the following chapters. In this type of review, the writer needs to be selective in what is presented, and the review may contain quite different points of discussion – it is typically broad in scope and brings together literature related to the context and theoretical underpinnings of the dissertation. To put together this type of review, it is necessary to take a very iterative approach to searching, and with separate topic searches, to explore literature in quite different areas. I’ve placed this type of review as a sort of opposite of a systematic review because it is quite different in both aims and methods: it is not addressing a narrow question in a reproducible way, but is rather the result of immersing yourself in prior literature, interpreting and situating your research within that prior work and thinking. Often a literature review chapter is presented with a thematic structure, and it is important to make clear the relevance of the points you make in the literature review to the rest of your dissertation.
These are just four review types, and I have simplified to an extent for the purposes of distinguishing features and underlying methods or approaches.
Grant, M. J., Booth A. (2009). "A typology of reviews: an analysis of 14 review types and associated methodologies." Health Info Libr J 26(2): 91-108. http://onlinelibrary.wiley.com/doi/10.1111/j.1471-1842.2009.00848.x/full [can help to decide what type of review to do among the systematic types]
Thomson, P. (2018). Why is writing a literature review such hard work? part two [blog post]. Retrieved from https://patthomson.net/2018/07/02/why%E2%80%8B-is-writing-a-literature-review-such-hard-work-part-tw... [especially useful for those not doing systematic reviews; see also Pat Thomson’s other blog posts on literature reviews (especially “avoiding the laundry list”). Aimed at PhD audience, but most points relevant to MSc dissertations.]
I’ve selected here three starting points for looking at literature review methods. The chapter by Thomas and Hodges provides a good overview to functions and types of literature reviews and I think is a good starting point to thinking of work toward a project like a dissertation. The article by Grant and Booth provides a breakdown of different types of reviews that take more or less systematic approaches and are more or less conducted with the aims of summarising evidence.
The blog post by Pat Thomson addresses mostly the type of review I characterised as the literature review chapter that supports a new piece of primary research. I recommend reading her other blog posts too – one of my favourites is on how to avoid the laundry-list type of literature review.
To reiterate my main points:
Literature reviews can have different functions, and depending on those functions, the methods or approaches will necessarily vary. It is important to select the type of literature review that best matches the function you need to have fulfilled. As a student, one of the most important things to remember is that the literature review is not just about the finished text which may show, or cite, just the tip of the proverbial literature iceberg you have read: the process or learning journey that you’ve experienced is just as valuable than the finished product and, finally, it does take time.