Key message: A scientific introduction
should arouse the reader's interest. It tells the reader what is being discussed and why she or he should read it.
A scientific article, a thesis or a PhD dissertation starts with a scientific introduction. A thesis or PhD dissertation is intended to solve a challenging problem from a scientific field using scientific methods.
Some guidelines specify that the introduction only contains background information that the reader needs to understand the work.
This sets the scene and describes the background to the study—what is already known about the topic, what are the gaps in knowledge, how the proposed study will add to this." (https://oxfordmedicine.com/view/10.1093/med/9780198599661.001.0001/med-9780198599661-chapter-004, 10.03.21)
Background/rationale ... Explain the scientific background and rationale for the investigation being reported
Objectives ... State specific objectives, including any prespecified hypotheses" (STROBE checklist for reporting observational studies: https://strobe-statement.org/fileadmin/Strobe/uploads/checklists/STROBE_checklist_v4_combined.pdf, 24.04.21)
It is a matter of choice whether the basic approach of the work is mentioned very briefly at the end of the introduction (this helps the reader to decide whether she wants to read the whole work). The detailed description of the approach is done in the chapter "Methods".
"Give the study's design but not the conclusion
This is a matter of choice, but I asked authors to give a one-sentence description of thei study at the end of the introduction. The last line might read:
We therefore conducted a double blind randomised study with 10-year follow up to determine whether ...
I don't like it; however, when the introduction also gives the final conclusion ..." (Smith, R. in Hall, G. (2003). How to Write a
Paper, London: BMJ Publishing Group, p. 13)
"We advise presenting key elements of study design early in the methods section (or at the end of the introduction) so that readers can understand the basics of the study." (Vandenbroucke JP, von Elm E, Altman DG, Gøtzsche PC, Mulrow CD et al. (2007) Strengthening the Reporting of Observational Studies in Epidemiology (STROBE): Explanation and Elaboration. PLoS Med 4(10): e297)
In an article about an empirical study, the introduction is immediately followed by the method section. If the study type is mentioned at the end of the introduction, it does not need to be mentioned again at the beginning of the method section. In a dissertation or thesis, the theory section is located between the introduction and the method section. There, a repetition would make sense.
Guidelines for writing a scientific article are the "instructions to authors" by scientifc journals and reporting guidlines for studies. For example: A list of reporting guidelines for medical studies endorsed by the EQUATOR Network can be found here.
1. The representation of the importance of the scientific work
A scientific work should deliver new knowledge and should be useful. If the work helps to solve an improtant problem it is of great benefit.
"Of course, the scientific significance is determined by how indispensable the new investigation is." (Eco, Umberto (2005). How to write a scientific thesis, Heidelberg: C. F. Müller)
A benefit always requires a need. So the introduction first describes the need for this work: What is the problem that this work wants to solve or wants to contribute to its solution? And why is it important to solve this problem?
Only in the rarest cases one scientific paper alone can solve an important problem. If the work refers to a larger general problem then it will only solve a specific problem (a subproblem). In the introduction, the specific problem must be named and explained. Whether I derive the specific problem from the general problem depends on whether the reader knows the context or not. The readers should not get bored by reading things they already know.
For example, there are many overweight people (that's the general problem). A study can examine whether a particular diet contributes to weight reduction (that's the specific problem).
The specific problem must be presented so clearly that the objective of the work can be deduced therefrom (in the second part of the introduction). Here are some sentences from the introduction to a book on literary interpretation:
"Interpretation has in recent years once again become the focus of literary criticism. ... Not only numerous writers but also literary scholars are systematically thinking about the usefulness of literature ... The starting point of [this book] is the question of the usefulness of literature and the interpretation of literature ... "(Schutte, J. (1993). Stuttgart, Weimar: Publisher JB Metzler)
The first of these sentences is a good starting sentence for an introduction. If it is not clear to every reader that interpretation has returned to center stage, this statement must be confirmed by arguments or references. Then the reason must be described, why the interpretation is the center of attention. With the previous findings on the interpretation of the literature, there seems to be a problem. The aim of the book is therefore to answer the question of the usefulness of literature.
In a thesis or PhD dissertation the presentation of the problem must be backed up by several references, because a scientific paper always points to the state of knowledge on a problem and then tries to add new findings. The author should show that at the beginning of his work he has carried out a review of the relevant literature and is able cite the essential references.
"The introduction must not include a review of the literature. Only cite those references that are essential to justify your proposed study. Three citations from different groups usually are enough to convince most assessors that some fact is 'well known' or 'well recognised' ..." (Hall, G. (2003). How to Write a Paper, London: BMJ Publishing Group, p.2)
A systematic literature search finds all important literature on a research question. Later, when the latest state of research is presented in the chapter on theory, this literature must be presented in more detail.
"When undertaking a systemativ review, an author poses a clear question, gathers all relevant information (publishes in whatever language or unpublished), discards the scientifically wear material, synthesis the remaining information and then draws a conclusion." (How to write a paper, Fith Edition. Edited by George M. Hall. Publishes 2013 by John Wiley & Sons, LtD., p. 8)
If the work deals with a topic that is not currently being discussed, it can nevertheless be very important for a small group of the population or for a single company. Or the topic may become important in the future and only then become the focus of public interest.
Other questions that can be answered in the introduction include: How did the problem arise? How has it evolved over time? Is the approach to the problem new in this work? ...
2. The representation of the objective of the work
After presenting the specific problem that the work wants to address, the objective of the work should be named and explained. The objective of the work is to contribute to the solution of this problem by adding new knowledge. If the problem was clearly described in the first part of the introduction, the objective of the work can be convincingly deduced.
The objective can be formulated as a statement: "The objective of the work is ..." or as a question: "The aim of the work is to answer the following question (research question): ....?" To solve the problem, a thesis can be set up, which should be proven by the work.
The theme of the work is the main idea or main subject of the work. A objective is a desired future outcome, which is precisely determined in terms of content, time and scope. According to this definition, the objective of the work must be precisely formulated. A reader (the supervisor) will not be satisfied with a vague goal formulation.
Most scientific papers, as well as theses and PhD dissertations, are limitd by the time and scope of the work, so the objective must be limited. For some theses the narrowing down to the objective belongs to the task. In such a case, the this should be explained along with the objective.
3. The representation of the way of proceeding
The next is a very brief description of how to proceed in order to achieve the
objective of the work (see above).
After describing the way of proceeding, the structure of the work (chapter by chapter) can be explained. Is the structure of the work a normal one, I personally consider such an explanation superfluous, since the reader can get a good overview on the basis of the table of contents. Reading the table of contents as text only costs the reader time and does not give him any advantage. An extraordinary structure of the work must of course be explained at this point.
How does a potential reader decide if she wants to read the paper or not? First he reads the title, then the table of contents, the introduction and the abstract. The order in which the last three are read depends on the reader's personal preference or specific question.
The introduction is of special importance, because it allows conclusions on the way the author works. Authors who work thoughtfully and carefully will not write a "confused" or boring introduction.
An introduction is boring if it make only generall statements or makes allegations that are not explained by appropriate references or practical examples. Optimal suitable references can only be found through a systematic review of the relevant literature (systematic review, see above).
A reader will think: If the author can write a short and interesting introduction, she also works precisely and he work is trustworthy (exceptions confirm the rule). Since not every person is gifted, the reverse is not true: despite a bad introduction, it can be a good work.
If I want to write a good introduction, I should read through the introduction at 5 - 10 finished scientific texts. Then it should be clear to me how pleasant it is to read a good introduction and that you should try to write a good one yourself (hopefully there was a good one among the ten introductions).
The works are written for interested professionals of the respective study program. This means that even the fellow students who are in their final year with the author must be able to understand and comprehend the work. Therefore, special technical terms in the introduction should only be used and defined when absolutely necessary to explain the problem, the objective or the way of proceeding. Such special technical terms are usually defined and explained in the theoretical body of the thesis.
A draft of the introduction should be written right at the beginning, because the clearer the problem and the goal and their background, the more goal-oriented the work can be done. "Good writers" know that writing a text is a process that takes time. A text needs to be revised several times before it is optimal. When I am working on my thesis or PhD dissertation, I should always think about how to write it down later.
"The introduction should be brief and must state clearly the question that you tried to answer in the study. ... Nevertheless, some studies seem to develop a life of their own, and the original objectives can easily be forgotten. I find it useful to ask collaborators from time to time what question we hope to answer. If I do not receive a short clear sentence as an answer, then alarm bells ring." (Hall, G. (2003). How to Write a Paper, London: BMJ Publishing Group, p.2)
Of course, only the plan of the work can be described in the draft of the introduction. Before submitting the work, the introduction must be thoroughly revised: The content, because the level of knowledge has deepened and because the work may have been carried out differently than planned. And the style, so that the introduction to the reader makes a good impression.
"Many research groups write the introduction to a paper before the work is started, but you must never ignore pertinent literature while the study is in progress." (Hall, G. (2003). How to Write a Paper, London: BMJ Publishing Group, p.2)