A great introduction can be key to winning at the peer-review process, and should answer three questions: 1-“What are you trying to prove?” 2-“Who Cares?” 3-“Could this possibly be true?”
Whether you like the peer review process or not, it is probable that for the present and near future peer review will be the only way to get your research published in high impact journals. I have seen great research fail to be published simply because the authors do not play the peer review process well. This series of articles is targeted at junior to mid-level researchers although experienced researchers may pick up a few tips as well. The articles give instructions on how to win the peer review process. They build upon my twenty years experience as a researcher and ten years experience as a statistician, reviewer, and research facilitator.
In this first article in the series, I will tackle how to write a winning introduction by focusing on three major questions every introduction should answer. I will also discuss some style issues.
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The first – and most important - purpose of the introduction is to answer for the reader and the reviewer this question: “What are you trying to prove?” Reviewing an article is not a fast or simple process. Most peer reviewers are busy people, and need to impressed at the outset by your article. For me, as a reviewer, nothing make reviewing an article more tedious and time-consuming than not really understanding what the article is trying to prove.
The best papers have a single objective and a single overarching hypothesis, or at the most a primary and secondary objective. For quantitative papers, my preference is to precisely spell out the null and alternative hypothesis in the last paragraph of the introduction, with a statement such as:
“The primary purpose of this study was to assess the impact of treatment with therapeutic steroids on pediatric migraine patients in the emergency department. The null hypothesis of no difference in migraine pain scale between the treated and untreated groups was compared to the alternative hypothesis of significant difference between groups.”
This leaves no doubt in the reviewers mind what the article is trying to prove.
For qualitative research, the last paragraph of the introduction should detail the purpose statement.
The second purpose of the introduction is to answer “who cares?” Remember that a journal's primary purpose is dissemination of information. Reviewers are always looking for “high impact” articles – articles that will effect a large number of readers. High impact articles are often called “practice altering.”
In this part of the introduction it is often helpful to cite information supporting the importance of your hypothesis. Does the topic concern a very common problem? For instance if your article is addressing how to improve the safety of buildings in an earthquake, cite information about the impact of earthquakes in terms of buildings affected or number of people affected. Does your study address an area of large financial impact? For a study addressing a decision rule on use of MRI, cite the financial costs of current MRI use.
The question “who cares” should also match the journal's mandate and audience. What's the ideal audience? People who should know some specific fact but don't already know it. Considering carefully the target journal can help. When writing the introduction, think about the target audience and explain to them how critical this information is.
The introduction needs to provide enough background to the reader and reviewer to answer the question “could this possibly be true?” Whether you follow the frequentist or Bayesian philosophy of statistics (or don't know the difference) one thing is true: statistics must be interpreted in the light of their pre-test probability. What does this mean? It means that statistics are most useful in testing a “Goldilocks” of hypotheses – a hypothesis that could possibly be true, but has not been already proven.
Failing to explain in the introduction that a hypothesis might be true can be a common reason for reviewers to reject outright of study results. Let's take a look at an absurd example that show this principle at work. Imagine a hypothesis where the probability that the hypothesis is true is very, very small. Perhaps we are looking at a study to prove that the earth is flat. Because previous research has shown pretty conclusively that the earth is not flat, it would take very compelling evidence to prove this wrong. In fact, all of us would recognize that in a study to reject the null hypothesis of “the earth is round” no p-value – no matter how small – would convince us to conclude the earth is flat. As absurd as this seems, I often see small studies that present novel results that contradict previous studies and yet do not explain why the study should be believed.
Conversely, some studies simply go on to prove a hypothesis based on facts that are already known or completely obvious. This is a study which tries to prove the earth is round. Again, the statistics of any study are not likely to challenge our previous beliefs. Again, as absurd as the example seems, this is a common problem. I see this commonly in educational studies where the hypothesis is that “knowledge improves after exposure to some training.” In this case it seems quite obvious that this must be true, and statistics here are not useful or interesting.
In many studies the goal is to prove causality. Examples might include concluding that a new medication leads to better survival from heart attack, a new teaching method leads to better mathematics grades, a new marketing approach leads to more customer orders, or a new beam structure leads to a more earthquake resistant building. Causality – in the statistical sense – requires three things: 1) consistency, 2) responsiveness, and 3) mechanism. If your article is attempting to prove causality, the introduction serves as a place to address these issues. To address consistency cite previous articles that have addressed the same or similar problems and how their results are similar to what your study is about to prove. If previous research has shown proof of responsiveness, cite that here as well. Finally, don't forget to address the mechanism. This is incredibly important for novel studies. Explain in some detail to the reader the mechanism underlying how the observation “y” could have been caused by “x.”
How do you write the “Goldilocks” of hypotheses in your introduction? If the study aims to present a new idea that contradicts current thinking, explain why you believe your study may be true. Describe the mechanism you feel may be at work. Detail any previous studies on the same or similar topic. If your study is attempting to confirm a truth that is already well researched, ensure that you describe any controversy in previous publications or why previous research may be incomplete.
What is not in an introduction? To keep the reviewer and reader focused on the results of your paper, your introduction should be focused. Unless you are writing a systematic review, the introduction is not a place to do an extensive literature review. Reviewers are usually not impressed by the number of articles cited in the introduction, and a large number of references in the introduction will not likely be seen as providing proof that your paper is important. Try to resist making the introduction into your own personal reading list. Although references to other articles can strengthen your argument, complicated or extensive references and comparisons might be better addressed in the discussion.
Remember that results of your study should never appear in the introduction. The introduction sets out the question addressed in the paper.
Sensitivity to the journal's style is a simple way to increase your chance of winning the peer review process. Many reviewers will know the journal style well, and will instantly spot any deviations. Read the “instructions to authors” carefully before submission. This includes how to cite references, label plots, etc.
When writing the introduction, keep the audience in mind. Generally I find the easiest approach is to imagine the reader as a colleague with similar education to yours but not the same speciality interest. For example, if you are writing an article about disaster response for a nursing journal, assume the reader is a nurse but does not have specific training in disaster medicine.
Remember that in general for the introduction clarity beats cleverness. Try to keep language and structure simple. If English is not your first language there is no need to be overwhelmed. Short simple sentences usually work best. I have worked with many excellent researchers with English as a second language, and the most common problem is not lack of knowledge of English grammar, but trying to make an introduction of elegant prose rather than simply spelling out the facts.
When should you write your introduction? Although I am addressing the introduction as the first topic in this series, it doesn't necessarily mean it must be written first. Many of my colleagues – including experienced researchers and journal editors – prefer to write the introduction last, only after writing the methods, results, and discussion. Many feel this allows them to write a more focused and relevant introduction. Personally, I have written articles in both ways. When the article is very focused with a single hypothesis and the methodology is determined prior to data collection (the way research should be done) I often write the introduction first. This allows me to keep in mind while writing the paper the focus of the article and to ensure that everything I write is directed at that focus. Conversely, articles that are of a more exploratory nature sometimes tend to develop themselves during the writing process and I have often delayed writing the introduction until the end.
Remember that the introduction will likely be the first contact reviewers will have with your manuscript. My experience has been that when reviewers are not convinced by the introduction that your study is important, the most likely outcome is rejection based on content. Usually, there is only one chance to impress the reviewer, as rejection based on content usually leaves no room for negotiation.
Reviewers can also be quite tenacious in their beliefs. My experience is that if a reviewer is adequately dissatisfied with any part of your paper to take the time to write a comment, it can be very, very hard to convince them that you were right and they are wrong. Prevention here is much easier than repair.
For many researchers, nothing is more frustrating than hours, days, or even years of time spent on research and not being able to have it published due to difficulties with the peer-review process. Spending a few extra moments ensuring that your introduction answers the questions of “what are you trying to prove?” “who cares?” and “could this possibly be true?” can help you win the peer review process.
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