Part III: Dissecting a Scientific Research Paper — the Introduction and Methods
The Introduction in a scientific manuscript is the section that provides background information on the topic, sets the context for the research, and provides an explanation for the study. In other words — it answers the question — “Why is this study being done?” It introduces the research question or hypothesis that is guiding the research and tells the reader what is being studied.
If you’ve been following along with this educational series, we’ve been using the article “Smoking Cessation, Weight Change, Type 2 Diabetes, and Mortality” as an example.
In the Introduction, we learn that quitting smoking reduces both the risk of developing major chronic diseases and extends how long a person is expected to live. People often gain weight after quitting smoking for several reasons. There’s not a lot of good, consistent information out there about the potential health consequences of gaining weight after quitting smoking. Therefore, this study was done to see if people’s chance of dying and developing type 2 diabetes increased after quitting smoking. And if so, if that increased risk was due to gaining weight.
An important thing to note — in the Introduction/Background and Discussion sections, you’ll often see a lot of citations — author names and years or hyper-script numbers which reference other papers and studies. This is how the authors demonstrate that what they are writing about in this section is based in fact! For example, when the authors of this paper claim that “weight gain may occur in quitters after cessation” (p. 624) — they are citing the article “Weight gain in smokers after quitting cigarettes: A meta-analysis” by HJ Aubin and others, published in 2012 in BMJ which found this statement to be true. Referencing other studies makes it easy for the reader to look up that study and confirm the authors’ findings. You’ll find all these citations at the end of the paper in the References section.
Now we have a bit of context as to why the study is being conducted!
The next section in a scientific manuscript is usually the Methods section — the part of the paper that tells us what the researchers did and how they did it. This section provides us with enough detail that we, as readers, could (theoretically) replicate this study, and can better understand their approach. Often, the Methods section is broken down into smaller sub-sections that provide information about how the study was designed, the participants that were included in the study, a description of what is being tested or examined, and how the data were collected and analyzed. Here, the Methods section is divided into the following shorter sections:
- Study population and study oversight
- Assessment of smoking status and weight change
- Assessment of physical activity and diet
- Assessment of outcomes
- Statistical analysis
What did we learn after reading through the Methods?
Where the data came from: We see that the researchers used data from groups of people who were participating in three long-term health studies: 1) Nurses’ Health Study, 2) Nurses’ Health Study II, and 3) Health Professionals Follow-up Study. (To learn more about these studies, click on the hyperlinks!) A total of 162,807 participants were included in the analysis about diabetes, and 170,723 participants were included in the mortality analysis.
In this study, there wasn’t a medication, test, or program that was being tested to see if it worked or not. Rather, the researchers were using information that was already being collected as part of those three large studies referenced above. Information about these individuals was collected through questionnaires that were mailed to them every 2 years. These questionnaires asked about their smoking status, weight change, physical activity, diet, and if they had diabetes. Information about mortality was pulled from different sources, such as death records and certificates. The researchers then used all this information to answer questions about diabetes and risk of dying after quitting smoking.
How the data was analyzed: The last part of the Methods section is the statistical analysis piece — how the data was analyzed. This is often one of the more challenging parts of a manuscript to understand. I often feel a bit out of my depth when I read this section of a manuscript, however, to help make up for my lack of statistical expertise, I routinely search out unfamiliar terms to better understand them. I’ve cited a few references I used which may be helpful:
Much like when you were in school and given a math problem to solve, the analysis section is like the “formula” you use to help figure out the answer to the question.
Next time we’ll look at the study Results!
ResearchMatch is here to help educate and empower our volunteers to take part in clinical trials and research studies. This includes understanding how their participation makes a difference and contributes to scientific discoveries. Interested in joining ResearchMatch? Click here to sign-up as a volunteer and be “matched” with research studies that are of interest to you!
Reference:
Hu Y, Zong G, Liu G, Wang M, Rosner B, Pan A, Willett WC, Manson JE, Hu FB, Sun Q. Smoking cessation, weight change, type 2 diabetes, and mortality. N Engl J Med 2018;379(7):623–632: doi: 10.1056/NEJMoa1803626.
Read the remaining installments of this educational series by clicking below:
