Ph.D. dissertations , or theses, come in many flavors.

At one end of the scale , they have the form of an introduction with chapters that follow each other in a logical, coherent way. Each of the chapters answers a research question, and these research questions are subquestions of one main research question.

At the other end of the scale, a dissertation or thesis consists of a number of previously published articles, with an introduction and conclusions or an epilogue at the end. These chapters loosely cover the same subject, but it is difficult to find a logical structure, or to define a main research question based on the individual research questions. This entry contains advice for an introduction for the latter type of dissertation.

I finished my Ph.D. dissertation, Design for Change, recently; it was definitely an example of the latter type. It contains eight chapters based on previously published articles, written over a long period of time, touching a broad set of subjects. Here, I describe how I tackled the problem of binding those chapters together in the introduction of the dissertation (I will use the word thesis from now on, because it is shorter).

Note that there are many more ways to write an introduction. The method that I describe comes handy when the range of subjects of the individual chapters is broad. It is difficult to write an introduction in such a situation.

What I will do here is:

• first show how to find subjects for individual parts of the introduction,
• then give tips on how to structure these parts into an introduction.

Subjects for individual parts

Creating the title of a thesis is extremely important: having a good title will help while writing the introduction. A good title is short, and covers the whole range of subjects from the individual chapters. The title may even help when you have to select which articles to use and which to discard.

In the remainder of this entry, we suppose that you have a (good) title.

Social and scientific interest

Start by describing the social and scientific interest, and at the same time, explain you title in a superficial way (the details will come later). By referring only to the title, you are forced to keep descriptions and explanations rather abstract and broad.

This first part of the introduction should seduce readers to read along. Showing the social impact of the subject you chose is a good way to do that.

You end this part with an overview of the remainder of the introduction.

Words of the title

Next, you could focus on each word of your title. What do you mean exactly with each word? Are there different interpretations? Is there a common ground in literature, about the meaning of the word? What is the history of its meaning?

In each case, you end by describing how you use the word in your thesis. Sometimes, you will use exact, formal definitions; sometimes the definitions will be vague. In the latter case, always make clear why you do not need a more precise definition.

Categorize your articles

When the subjects of your individual articles lie much apart, you may consider trying to categorize them into two or three categories.

To find these categories may be hard. You may use a spreadsheet, and list your articles vertically, and every aspect that you might think of horizontally.  Then look if there are aspects, or combinations of aspects, that divide the articles equally. This will take time! Often, you will wake up one morning and just know how to categorize them.

Each category now can become a part of the introduction. In each of these parts, you show how each of the chapters or articles fits in that category. You also relate the words of your title to each category.

You may consider dividing your thesis into parts, based on your categories.

A list of chapters

The last part of your introduction will become a list of chapters. Of each chapter, you mention the details of the publication it is based upon, and  if you are not the main author, you give a short description of your contributions. You mau also add a short description of the contents.

The structure

Now, you have to find a balance between many sections without subsections, and few sections with many subsections (and subsubsections, etc): between a broad and deep structure.

In general, try to avoid subsubsections. If these subsubsections are small, you are better of using a description list, or a paragraph with the first sentence in bold.

Often, you will make an argument in your introduction. In such a case, read The Pyramid Principle of Barbara Minto. This wil, help you writing the parts, and it will also help to fund the right structure.

Of course, these tips will not help in every case. But they might get you started. Once you have something on paper, it is always easier to build a coherent introduction than when you sit in front of a blank paper.