Hi.
This is Karen McKee with another video about scientific writing.
Whether you are writing a term paper, a thesis, a grant proposal, or an article for publication
in a journal, you will need to do a literature review.
If you’ve never done a literature review before, then you may be at a loss as to how
to go about it.
But don’t worry.
In this video, I’m going to show you how to conduct a literature search online and
then how to organize and write the review.
Although I’ll be using the scientific literature to illustrate, the general approach applies
to other academic fields.
But first, it’s important to be clear about why you are doing a literature review.
Your main objectives are to summarize the relevant literature related to your research.
Synthesize past and current research as it relates to specific concepts and processes
relevant to your research.
Identify unanswered questions, gaps or contradictory studies in the field.
And show how your research fits in.
In a research paper or thesis, your literature review sets the stage for your research findings.
This means you must make choices about what to cite.
You want to be judicious in your selections.
In general, you want to choose papers that are relevant and recent, but it’s also okay
to cite a much older classic paper that provides historical perspective, for example.
Or there may be a long-established theory or concept that your work addresses.
You would want to cite key papers that introduced and advanced those concepts.
Cited journal articles need to show how your research fits into the broader field, but
you can’t cite everything written on the topic.
In this paper, for example, we referenced about 30 papers in the introduction and about
60 overall.
Other types of writing, such as a review article, may differ in scope, length, and purpose.
This recent review cited over 200 papers and went into greater depth in synthesizing all
of the relevant literature on the topic.
By the way, a recent review paper on your topic can be a great place to start in preparing
to write your literature review.
It can give you an overview of the topic.
Summarize important concepts and controversies.
And identify key papers to focus on.
Okay.
Now that we have some idea of what a literature review entails, let’s see how to conduct
a literature search.
Back in the dark ages when I was a student, this is where we did our searching.
In the library stacks, physically tracking down journal issues containing the paper we
wanted to read.
Luckily, you now have the internet and online platforms for searching the scientific literature
such as Web of Science, Google Scholar, or PubMed for biomedical research.
I’m going to be using Web of Science, which is what I have access to through my institution,
but the basic search methods are similar on all these platforms.
There may be several databases, depending on your institution, but most scientists will
use the Web of Science Core Collection.
And we’ll start with the basic search option.
Note that you can select the time period, which may help you to limit the search to
more recent papers.
You can search for terms in different fields such as topic, title, author, year and so
forth.
Let’s say I want to search for papers about soil factors affecting the growth of mangrove
tree seedlings.
I’ll type in mangrove, but we also want variations such as mangroves or mangal.
So I use a Boolean operator OR between these terms.
Next, I’ll add a second search term, soil and also variations such as edaphic and physicochemical
Finally, I’ll add the third search term.
Note we can also search for a phrase in quotation marks such as seedling growth.
But in this case, I’ll just add an asterisk, which will create a wild card to look for
plural forms and different spellings of words.
Click search and we get 212 papers.
Maybe I want to limit this search to papers in which some terms appear only in the title.
So let’s change the search field from topic to title for two of the search terms.
Now the search will focus on papers with mangrove and seedling or their variations in the title
and soil terms in the abstract or keywords.
This search returns 31 papers.
You would then go through the list and look at each abstract to decide if this is a paper
you need to read.
This one for example looked at how soil salinity affected mangrove seedling growth.
If salinity is something of interest, then we can find more papers like this by looking
at the papers this paper cited plus those papers that later cited this paper.
We can click on the paper’s citations, and we see all 51 papers.
We can also take a look at the 19 papers that cited this one.
You may find relevant papers that did not appear in the original search using keywords.
You can also conduct a search for citations of specific papers using the cited reference
search.
Finally, there’s the advanced search.
Here, you’ll use field tags listed along with Boolean operators to set up a search.
For example, we’d type in TI for title equals mangrove followed by an asterisk.
And seedling in parentheses.
And TS for topic equals soil or edaphic in parentheses.
Click search.
And we get 27 results.
Click on that number to view those papers.
Of course, as you locate papers you potentially wish to cite, it’s a good idea to export
the citation to a bibliographic system such as Endnote.
To do this select export and choose your option.
I’ll export to Endnote Desktop which is what I have.
And you can export the entire record or just the citation
and abstract.
Then, all I have to do is import that file and it appears in my Endnote library.
I’ll open it up and double check the imported information.
After searching the literature, you end up with a stack of papers.
The next step is to get organized in your reading.
You want to identify and read major works first, followed by later works that built
upon or refuted early papers.
As I mentioned before, a recent review paper can help you get an overview of the topic
and which papers introduced key concepts or made important advances.
I should point out here that experienced researchers have been reading the literature all along
and already have a good idea as to what’s out there.
They just need to do a search for any papers they may have overlooked.
As you read, it’s a good idea to take notes.
Here, I type in some specific points I might want to later describe.
Once you’ve finished reading and organizing the relevant literature, you are ready to
write.
How you structure the literature review depends on what you are writing.
We’ll use the literature review for a research article as an example.
In a research article, the literature review is part of the introduction.
Here is the paper I mentioned earlier which illustrates how a literature review is woven
into the introduction.
First, background literature is used to introduce the broad research topic.
In this case, I used a few papers written about different plant communities to introduce
the concept of facilitation.
In the next paragraph, I described why information about facilitation can enhance restoration
practices.
Next comes a review of progress or status of the topic.
This can be organized by theme or chronologically.
In this paper, I explained that progress had been limited by a lack of studies about facilitation
in the context of restoration.
The review should then compare and contrast the literature to identify any controversies
or key questions that must be addressed to move the field forward.
In the fourth paragraph, I focus the reader’s attention on the question of whether facilitation
depends on the species providing the beneficial effects.
Once a question or controversy has been identified, then studies that address this key point should
be compared and contrasted.
In the fifth paragraph, I described examples of where facilitation had been studied.
The review must then narrow the focus to the specific system studied and describe what
research has so far been done that justifies further scrutiny.
In this paper, I described the mangrove ecosystem we studied and why it was chosen.
In doing so, it was only necessary to provide a few citations to support the argument that
while some information existed about factors controlling mangrove growth and distribution,
there was little work on facilitation.
The idea is to set the stage for your study and how you tackled the key question identified
in your literature review, here described in the final paragraph of the introduction.
Well, that’s a basic structure for a literature review, but you may still be wondering how
to physically write it sentence by sentence.
Let’s take a closer look at this using the first two paragraphs of the example paper.
In writing this opening, I already had a good idea of the literature on plant interactions
and what I wanted to say.
I began by describing well-known processes controlling plant reestablishment after a
disturbance.
These are statements that don’t really require citations because of their general nature.
In the last sentence, though, I wanted to contrast competition, which is widely recognized
as an organizing force, with the topic of our study, which was facilitation.
This is a statement that requires citations.
So I wrote that facilitation was a mechanism that also influences plant distribution and
success.
I knew from my reading that this was the case and that the statement needed one or more
citations.
I cited more than one paper, several of them reviews, to make the point that facilitation
was not a rare mechanism, but one considered to be important by plant ecologists.
In the next paragraph, I summarized examples of situations in which nurse plants enhanced
seedling recruitment in a variety of ways.
These all resulted from a literature search using the term nurse plant or nurse species
and seedling.
Then all I needed to do was list the various mechanisms such as seed trapping, amelioration
of soil conditions, etc. along with the relevant citations.
I continued methodically working my way through the review this way, stopping periodically
to reread a paper or to look up a specific point.
I should mention here that if you are working in a fast-moving field, it’s a good idea
to continually rerun your literature search to catch any late-breaking papers.
So to summarize, knowing how to efficiently conduct a literature search and then use that
material to write a coherent literature review are important skills for any scholar.
Like most academic writing, such skills take practice to perfect.
Your first attempt may not go smoothly, but don’t get discouraged.
The more you practice, the better you will get and the easier it will be to summarize
the literature on a particular topic.
Thanks for watching and don’t forget to like my video if you found it helpful.