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How To Write A PhD Dissertation/ Thesis

So the time has come to write your Ph.D. dissertation has it? Well, good; this is an exciting time for you – but unless you’ve written similar formal documents before, you may be in for a bit of a shock: it's difficult!

Don’t worry, though, there are ways you can succeed:

  • You could try to out your last research committee; grind them down to your way of thinking. They’re old, right? The bad news is, they are experienced, too. They’ve survived their own research committees for this position and they’re not going to give up easily.

You might need Plan B.

  • Plan B is to plan ahead. I like Plan B because it puts you in control. It gets you straight through your dissertation research and writing and through your dissertation defence as quickly as possible. Bad news if you had in mind a cushy but poverty-stricken career as a graduate student.

Here are a few guidelines that may help you when you finally decide you want to pass your dissertation defence, maybe for the sake of your wallet or your liver.


What is a PhD dissertation about?

A PhD should put forward a defence of a hypothesis or an idea. The work included in your PhD dissertation needs to be both original and substantial; it needs to say something new.

Most PhD dissertations take the scientific route of starting with a hypothesis and then collecting evidence to support or deny it. You’ve got to collect the evidence in support of your hypothesis before you can write up your dissertation. The most difficult aspect of writing a dissertation is organizing this evidence and the discussion of it into a coherent form. The focus of your dissertation should be on your discussion of your scientific, empirical findings. Your results only matter in so much as they support your hypothesis. You need to think critically and the only way your results mean anything all in terms of your dissertation is if you discuss them fully; therefore, the analysis should be at the very heart of your dissertation.

A dissertation concentrates on principles: it states the lessons learned, and not merely the facts behind them.
Every point you make in your dissertation has to be supported either by a reference to earlier research in your field or your original primary research. A dissertation has to say something new about these findings, not simply regurgitate what has already been published.

A dissertation is a formal document and needs to be well written, grammatically correct and with good spelling and punctuation. As a formal document, unlike this one, it has certain extra criteria which it must meet:

  • No contractions (isn’t, hasn’t, etc)

  • No colloquialisms

  • No undefined technical jargon

  • No hidden jokes

  • No slang, even those in common usage

The writing in a dissertation needs to be as clear as possible. You may have to make fine distinctions between results and arguments and your terminology must be equal to the challenge. This probably goes without saying but for the sake of completeness I will say it anyway - each statement that you make in your dissertation needs to be correct and defensible logically and scientifically. Your discussion within your dissertation needs to be scrupulously logical, with each point following from the next and all firmly grounded in your primary research results.

A PhD dissertation is good experience for communicating your ideas to other professionals. It is a challenge which requires you to think deeply and organize your thoughts logically and fully on paper. You need to follow rules for rigorous, formal presentation of arguments and discussion. Good writing is essential; however, it is your ideas which count the most; no amount of good written language will compensate for you not having anything constructive and useful to say. You will find that if your dissertation is written well and clearly, it will be even more obvious if you do not have adequate points to make or if you lack evidence to support your arguments.


Definitions and terminology

You should define each technical term that you use in your dissertation. These definitions must be written either by a reference to a previously published definition (for standard terms with their usual meaning) or by a precise, unambiguous definition that appears before the term is used (for a new term or a standard term used in an unusual way). The way you use these terms should remain constant throughout your dissertation in order to avoid ambiguity.

If you feel that your dissertation requires a lot of definitions and you have derived your definitions from a single source, you could perhaps save yourself some time and effort by including a statement such as: “the terminology used throughout this document follows that given in [CITATION].” Then, you only need to define exceptions.

Terms and phrases to avoid

  • Adverbs – if you use the correct, meaningful, verb, adjectives are surplus to requirements

  • Jokes or puns – not everyone will share your sense of humour and they can detract from your dissertation argument

  • Judgemental words – you should be precise in your wording and avoid qualitative judgements within your dissertation

  • “Today”, “soon” etc – your dissertation will hopefully be read long into the future and these terms “soon” become meaningless

  • “Seems” – it doesn’t matter how something seems; be specific and be definite

  • “Claim/claims” – as in, for example, “Johnson and Smith [J&S90] reports that...'' The word ‘claim’ casts doubt upon these findings as if they were not true


Avoid all colloquialisms – they sound like you’re not taking your research seriously and they can also make it difficult for your dissertation to be understood by an international audience and even by readers from another region within your own native country.

  • “A number of'” – How many do you mean? You need to be quantitative.

  • “Obviously”, “clearly” – Obvious or clear to whom? It’s never a good idea to try to make your reader feel stupid because they didn’t follow your argument; it could just be that your argument was flawed.

  • “Along with” – Just “with” is perfectly adequate

  • “Actually, really” - define terms precisely and there should be no need to clarify

Never use the second person – “you”
Never use the first person – “I”

  • “We” – this can be unspecific and cause confusion; does it mean “we” as in the author and reader; “we” as in the author and advisor” or “we” as in those of us in this particular academic discipline; there are a lot of groups and pairings to whom this could refer and so it is unspecific.

  • “...a famous researcher...'' – who? Be specific and leave out the qualitative judgement about how well known they are.

  • “Few, most, all, any, every” – a dissertation needs to be specific.

  • “Must”; “should”; “always” – these are judgemental and often inaccurate.

  • “Proof”; “prove” – would a mathematician agree that this is proof?

  • “can/may” – ask your mother if you don’t know the difference!

OK, so that has warned you off lots of things you should not say within your dissertation; now let us get positive again; how should you phrase your dissertation so that it presents as clear and compelling an argument as possible?



Within a formal dissertation you should always use the active voice. For example, you should write “the operating system starts the device” instead of writing “the device is started by the operating system.” This is a much more direct and clear way of writing and helps to avoid ambiguity; it will make you sound more certain too, which is useful when you want to present a compelling argument within your dissertation.



You should write in the present tense. This helps to make your research sound current – whenever it is read and so it increases its relevance to the reader and helps them to accord your dissertation greater credence.

Define negation early
Do not keep your reader in suspense if your sentence is a negative one. State the negative right away in the sentences; for example, write “no data block waits on the output queue” instead of “a data block awaiting output is not on the queue”.

Use grammar logically
One very important part of writing a dissertation is clear expression. Correct sentence structure is essential to logical argument; therefore, you should be careful that the subject of each sentence really does what the verb says it does. Saying “Programs must make procedure calls using the X instruction” is not the same as saying “Programs must use the X instruction when they call a procedure”.

Unfortunately the rules of logic are often difficult to follow when the language of discourse is English instead of mathematical symbols. You should be very careful that you are saying exactly what you want to say, clearly and unambiguously without any room for other interpretations of your words. This can be quite daunting if you leave it until your final proofreading at the end of writing process to check that every one of your sentences is clear and unambiguous. You would be well advised to check this much more frequently – after every paragraph, perhaps. This will get you into the habit of checking your work and you will also begin to get more of a sense when your logic has strayed if you check this frequently; also, if changes need to be made for one paragraph, this is not as daunting as if you needed to re-write major parts throughout your dissertation.

Be results focused
The results of your personal, primary research should be the main focus of your dissertation; all the dissertation write-up should stem from the results of your research.

Do not make it personal
You should resist the temptation to personalize your research. You should want your research to appeal to as wide and large a group of people as possible, and personal details of your research struggles have no place in the dissertation in that case. It doesn’t matter what struggles you went through in your research process or how angry you were with yourself over the mistakes you made or even how tired you were from all those long hours in the lab; the vast majority of your readers won’t care about this and all you will succeed in doing by including these extraneous details is confuse your readers.

The people behind the research don’t matter. Of course, if you receive help along the way from someone else then you need to include their name(s) in the Acknowledgements section of your dissertation, but you should not include names (even your own) in the main body of your dissertation.

You may be tempted to document within your dissertation a long series of experiments that do nothing to prove your hypothesis, but you should resist that temptation.  It will detract from the overall thrust of your argument.

Your readers don’t need to know about any coincidences that result in successful progress with your dissertation; including such things that will weaken your dissertation.

You should confine yourself within your dissertation to stating your factual observations and discussing points which can be logically deduced from these observations.

You should never attribute your findings to mystical causes or imply that strange forces may have affected your results; stick to the facts. Describe the results without dwelling on your reactions or on the events that helped you achieve them.


Avoid self-assessment

You should never either praise or criticize the method by which you conducted your research; such comments have no place within the body of your dissertation. Criticizing your method weakens the arguments contained within your dissertation; praising your method can sound arrogant and readers will then have a tendency to pick fault with the method of which you are so proud, thus also weakening your argument.



One should always cite papers, not authors. Thus, it is correct to use a singular verb to refer to a paper even though it has multiple authors. For example ``Johnson and Smith [J&S90] reports that...''


Terminology for Concepts and Abstractions

When defining the terminology for a concept, be careful to decide precisely how the idea is implemented. If you will need to discuss the differences between a concept and its implementation within your dissertation, your definitions must allow such a distinction.

Knowledge vs. data
The facts that result from an experiment are called “data”. The term “knowledge” implies that the facts have been analyzed in some way to form useful arguments, so be careful how you use these terms.


Cause and Effect
A fundamental aspect of a dissertation is the careful separation of cause and effect relationships from simple statistical correlations. If you state that something is a cause and effect relationship them you must be very clear that Y arises as a result of X, not simply that there is some correlation between X and Y.

This point is linked to the next:

You should only draw logical conclusions
Your conclusions must always arise from supporting evidence. Even if the cause of some phenomenon seems obvious, you should not draw a conclusion without solid, supporting evidence.

In a dissertation, you should never draw conclusions about the economic viability or commercial success of an idea or method. You must remain objective about the merits of an idea independent of its commercial popularity. You should be particularly careful not to confuse commercial success with merit. Many commercially viable projects have little merit outside of this and likewise, many projects which would be very useful receive little economic reward.

You should avoid all political influence when assessing the ideas contained within your dissertation. It should be of no relevance whether government bodies, political parties, religious groups or other organizations endorse an idea within your dissertation.

This point should give you confidence, though, because it is often overlooked but it is still true that it does not matter whether an idea originated with a scientist who has already won a Nobel Prize or a first-year graduate student. The merits of an idea need to be assessed independently of the source.


Organizing your dissertation

Every dissertation needs to define the problem which is the basis of your research. What problem motivated you to embark upon your dissertation research? You should be able to tell readers of your dissertation why the problem is important. You also need to give an account of what research has previously been carried out within this area. How does your original research offer a meaningful contribution to what has been written before? Within a dissertation you need to clearly document the experiments that you carry out and which validate your research and help you draw your original conclusions.

There is not only one way to organize your dissertation; however, the framework that follows is a good starting point:

Chapter 1: Introduction
The introduction should provide an overview of the problem that you are researching. Your dissertation’s opening chapter should tell your reader why your dissertation question is an important one to research; it should set your current research against a background of prior research in this area, state your specific research hypothesis and show how your dissertation will be breaking new ground. You should make the introduction to your dissertation readable and accessible to anyone so that they are encouraged to read on further.

Chapter 2: Definitions
This is the section where you should define any new terms which you are introducing as a result of your research. You should take care to make your definitions are precise and short. They should be easily understood with no room for ambiguity.

Chapter 3: Conceptual Model
Here you should present a theme that links together all your ideas and arguments. This should be a central concept which underlies all the work contained within your dissertation. Here you should provide an answer to the question posed in the introduction at a conceptual level. If necessary, you should add another chapter to give additional reasoning about the problem or its solution.

Chapter 4: Experimental Measurements
You need to describe the results of your experiments – but only those which provide evidence in support of your thesis. Do not confuse your reader here with contradictory results.

Your results can either:

a. prove your concepts


b. demonstrate that your original method is more efficient than those which already exist

Chapter 5: Corollaries and Consequences
Here you need to describe and discuss variations and extensions of the central idea of your dissertation and discuss their practical applications.

Chapter 6: Conclusions
On this section you should summarize what was learned through your research and the writing up of your dissertation; you should demonstrate how this knowledge can be applied. You should mention the possibilities for future research.



This will be the most widely read section of your dissertation. People will come here first to see if your research is relevant to their interests and from there decide whether or not if they wish to read your entire dissertation. Your abstract should only consist of a few short paragraphs which summarize the rest of your dissertation. You need to describe the problem and give brief details of your research approach. Within the abstract you should emphasize your original contributions, not so much the background to your research.


Suggested Order for Writing

You should not begin at the first page and end at the last page when writing your dissertation. For instance, your abstract should be written last as it has to summarize your entire research project and that will only be known towards the end of your dissertation.

The easiest way to attempt the writing up of a dissertation is with a part of your dissertation you feel most comfortable with; this will help to build your confidence and fend off writer’s block. Usually, Chapters 3, 4 and 5 above are the easiest to write because they are a description of the research process in which you were so intimately involved; you ought to be able to write about this quite comfortably. As each new term arises in this write up, make a note of it and its definition. Every technical term that you use in your dissertation should be defined, even if it is used in the conventional way which people are likely to understand. You need to remove all that ambiguities that you can.

Your definitions should be organized in a chapter all of their own; they should be precise and written formally. As you write each definition, you should check all the chapters of your dissertation in order to ensure that your definitions are used consistently and that you don’t imply a different definition when you use the concept elsewhere in your dissertation.

Next you should write your conclusions, which will pull together and clarify all the main arguments which you make in the main body of your dissertation.
Your introduction should be written next, when you have the main body of your dissertation written; that way you know what your introduction needs to lead into and what ideas need to be raised in order for your readers to be prepared for reading the rest of your dissertation.
Finally, the abstract which summarises your entire dissertation should be written.


Practice makes perfect

The only way to learn to write your dissertation properly is to practice that writing. Draft and re-draft your work in each section until you are happy with it. Write something towards your dissertation every day and that way you will make steady progress, making your dissertation as well-written as you possibly can.


Finally – take it from a few who know:

After great pain, a formal feeling comes.
-- Emily Dickinson

A man may write at any time, if he will set himself doggedly to it.
-- Samuel Johnson

Keep right on to the end of the road.
-- Harry Lauder

The average Ph.D. thesis is nothing but the transference of bones from one graveyard to another.
-- Frank J. Dobie


If those quotations mean nothing to you at the moment, read them again after you have written your dissertation and see if you have changed your min



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