How to Write a PhD Thesis
Joe
Wolfe
School
of Physics
The University of New South Wales, Sydney
 Spanish version: CÛmo escribir una tesis de doctorado
French version: Comment rediger une thèse
- This guide to thesis writing gives simple and practical advice
on the problems of getting started, getting organised, dividing
the huge task into less formidable pieces and working on those
pieces. It also explains the practicalities of surviving the
ordeal. It includes a suggested structure and a guide to what
should go in each section. It was originally written for graduate
students in physics, and most of the specific examples given are
taken from that discipline. Nevertheless, the feedback from users
indicates that it has been widely used and appreciated by graduate
students in diverse fields in the sciences and humanities.
- Getting
started
- What is a
thesis? For whom is it written? How should it be written?
- Thesis
Structure
- How to
survive a thesis defence
Getting StartedWhen you are about to begin, writing a
thesis seems a long, difficult task. That is because it is a long,
difficult task. Fortunately, it will seem less daunting once you
have a couple of chapters done. Towards the end, you will even
find yourself enjoying it---an enjoyment based on satisfaction in
the achievement, pleasure in the improvement in your technical
writing, and of course the approaching end. Like many tasks,
thesis writing usually seems worst before you begin, so let us
look at how you should make a start.
An outlineFirst make up a thesis outline: several
pages containing chapter headings, sub-headings, some figure
titles (to indicate which results go where) and perhaps some other
notes and comments. There is a section on chapter order and thesis
structure at the end of this text. Once you have a list of
chapters and, under each chapter heading, a reasonably complete
list of things to be reported or explained, you have struck a
great blow against writer's block. When you sit down to type, your
aim is no longer a thesis---a daunting goal---but something
simpler. Your new aim is just to write a paragraph or section
about one of your subheadings. It helps to start with an easy one:
this gets you into the habit of writing and gives you
self-confidence. Often the Materials and Methods chapter is the
easiest to write---just write down what you did; carefully,
formally and in a logical order.
How do you make an outline of a chapter? For most of them, you
might try the method that I use for writing papers, and which I
learned from my thesis adviser: assemble all the figures that you
will use in it and put them in the order that you would use if you
were going to explain to someone what they all meant. You might as
well rehearse explaining it to someone else---after all you will
probably give several talks based on your thesis work. Once you
have found the most logical order, note down the key words of your
explanation. These key words provide a skeleton for much of your
chapter outline.
Once you have an outline, discuss it with your adviser. This
step is important: s/he will have useful suggestions, but it also
serves notice that s/he can expect a steady flow of chapter drafts
that will make high priority demands on his/her time. Once you and
your adviser have agreed on a logical structure, s/he will need a
copy of this outline for reference when reading the chapters which
you will probably present out of order. If you have a co-adviser,
discuss the outline with him/her as well, and present all chapters
to both advisers for comments.
OrganisationIt is encouraging and helpful to start a
filing system. Open a word-processor file for each chapter and
one for the references. You can put notes in these files, as
well as text. While doing something for Chapter n, you will think
"Oh I must refer back to/discuss this in Chapter m" and so you put
a note to do so in the file for Chapter m. Or you may think of
something interesting or relevant for that chapter. When you come
to work on Chapter m, the more such notes you have accumulated,
the easier it will be to write.
Make a back-up of these files and do so every day at
least (depending on the reliability of your computer and the
age of your disk drive). Do not keep back-up disks close to the
computer in case the hypothetical thief who fancies your computer
decides that s/he could use some disks as well.
A simple way of making a remote back-up is to send it as an
email attachment to a consenting email correspondent, preferably
one in a different location. You could even send it to yourself if
your server saves your mail (in some email packages like Eudora
this is an optional setting). In either case, be careful to
dispose of superseded versions so that you don't waste disk space,
especially if you have bitmap images or other large files.
You should also have a physical filing system: a collection of
folders with chapter numbers on them. This will make you feel good
about getting started and also help clean up your desk. Your files
will contain not just the plots of results and pages of
calculations, but all sorts of old notes, references, calibration
curves, suppliers' addresses, specifications, speculations,
letters from colleagues etc., which will suddenly strike you as
relevant to one chapter or other. Stick them in that folder. Then
put all the folders in a box or a filing cabinet. As you write
bits and pieces of text, place the hard copy, the figures etc in
these folders as well. Touch them and feel their thickness from
time to time---ah, the thesis is taking shape.
If any of your data exist only on paper, copy them and keep the
copy in a different location. Consider making a copy of your lab
book. This has another purpose beyond security: usually the lab
book stays in the lab, but you may want a copy for your own future
use. Further, scientific ethics require you to keep lab books and
original data for at least ten years, and a copy is more likely to
be found if two copies exist.
While you are getting organised, you should deal with any
university paperwork. Examiners have to be nominated and they have
to agree to serve. Various forms are required by your department
and by the university administration. Make sure that the rate
limiting step is your production of the thesis, and not some minor
bureaucratic problem.
A note about word processorsOne of the big FAQs for
scientists: is there a word processor, ideally one compatible with
MS Word, but which allows you to type mathematical symbols and
equations conveniently? One solution is LaTeX, which is powerful,
elegant, reliable, fast and free from http://www.latex-project.org/
or http://www.miktex.org/. As
far as I know, the only equation editor for MS Word is slow and
awkward. (If anyone knows a way of writing equations in this
software without using the mouse, many people including this
author would like to hear from you!) Another solution is to use
old versions of commercial software. Word 5.1 allows equations to
be typed comfortably: it is faster in this respect than LaTeX,
with the added advantage of 'what you see is what you get'
(WYSIWYG). (If anyone knows how to run Word 5.1 on OSX, please let
me know!) A search will find sites that provide discontinued
software, but, not knowing whether this is legal or not, I shan't
link to them. (I am told that LyX, available free at
http://www.lyx.org/, is a convenient front-end to LaTeX that has
WYSIWYG. )
Commercial word processors have gradually become bigger,
slower, less reliable and more awkward to use as they acquire more
features. This is a general feature of commercial software and an
important input to the computing industry. If software and
operating system performance did not deteriorate, people would not
need to buy new computers and profits would fall for makers of
both hard- and soft-ware. Software vendors want it to look fancy
and obvious in the demo, and they don't really care about its
ease, speed and reliability to an expert user because the expert
user has already bought it. In our example, it is much faster to
type equations and to do formatting with embedded commands because
you use your fingers independently rather than your hand and
because your fingers don't leave the keyboard. However, click-on
menus, although they are slow and cumbersome when typing, look
easy to use in the shop.
A timetableI strongly recommend sitting down with the
adviser and making up a timetable for writing it: a list of dates
for when you will give the first and second drafts of each chapter
to your adviser(s). This structures your time and provides
intermediate targets. If you merely aim "to have the whole thing
done by [some distant date]", you can deceive yourself and
procrastinate more easily. If you have told your adviser that you
will deliver a first draft of chapter 3 on Wednesday, it focuses
your attention.
You may want to make your timetable into a chart with items
that you can check off as you have finished them. This is
particularly useful towards the end of the thesis when you find
there will be quite a few loose ends here and there.
Iterative solutionWhenever you sit down to write, it
is very important to write something. So write something,
even if it is just a set of notes or a few paragraphs of text that
you would never show to anyone else. It would be nice if clear,
precise prose leapt easily from the keyboard, but it usually does
not. Most of us find it easier, however, to improve something that
is already written than to produce text from nothing. So put down
a draft (as rough as you like) for your own purposes, then clean
it up for your adviser to read. Word-processors are wonderful in
this regard: in the first draft you do not have to start at the
beginning, you can leave gaps, you can put in little notes to
yourself, and then you can clean it all up later.
Your adviser will expect to read each chapter in draft form.
S/he will then return it to you with suggestions and comments.
Do not be upset if a chapter---especially the first one you
write--- returns covered in red ink. Your adviser will want
your thesis to be as good as possible, because his/her reputation
as well as yours is affected. Scientific writing is a difficult
art, and it takes a while to learn. As a consequence, there will
be many ways in which your first draft can be improved. So take a
positive attitude to all the scribbles with which your adviser
decorates your text: each comment tells you a way in which you can
make your thesis better.
As you write your thesis, your scientific writing is almost
certain to improve. Even for native speakers of English who write
very well in other styles, one notices an enormous improvement in
the first drafts from the first to the last chapter written. The
process of writing the thesis is like a course in scientific
writing, and in that sense each chapter is like an assignment in
which you are taught, but not assessed. Remember, only the final
draft is assessed: the more comments your adviser adds to first or
second draft, the better.
Before you submit a draft to your adviser, run a spell check so
that s/he does not waste time on those. If you have any
characteristic grammatical failings, check for them.
What is a thesis? For whom is it written? How should it be
written?Your thesis is a research report. The report
concerns a problem or series of problems in your area of research
and it should describe what was known about it previously, what
you did towards solving it, what you think your results mean, and
where or how further progress in the field can be made. Do not
carry over your ideas from undergraduate assessment: a thesis is
not an answer to an assignment question. One important difference
is this: the reader of an assignment is usually the one who has
set it. S/he already knows the answer (or one of the answers), not
to mention the background, the literature, the assumptions and
theories and the strengths and weaknesses of them. The readers of
a thesis do not know what the "answer" is. If the thesis is for a
PhD, the university requires that it make an original contribution
to human knowledge: your research must discover something hitherto
unknown.
Obviously your examiners will read the thesis. They will be
experts in the general field of your thesis but, on the exact
topic of your thesis, you are the world expert. Keep this in mind:
you should write to make the topic clear to a reader who has not
spent most of the last three years thinking about it.
Your thesis will also be used as a scientific report and
consulted by future workers in your laboratory who will want to
know, in detail, what you did. Theses are occasionally consulted
by people from other institutions, and the library sends microfilm
versions if requested (yes, still). More commonly theses are now
stored in an entirely digital form. These may be stored as .pdf
files on a server at your university. The advantage is that your
thesis can be consulted much more easily by researchers around the
world. (See e.g. Australian
digital thesis project for the digital availability of
research theses.) Write with these possibilities in mind.
It is often helpful to have someone other than your adviser(s)
read some sections of the thesis, particularly the introduction
and conclusion chapters. It may also be appropriate to ask other
members of staff to read some sections of the thesis which they
may find relevant or of interest, as they may be able to make
valuable contributions. In either case, only give them revised
versions, so that they do not waste time correcting your grammar,
spelling, poor construction or presentation.
How much detail?The short answer is: rather more than
for a scientific paper. Once your thesis has been assessed and
your friends have read the first three pages, the only further
readers are likely to be people who are seriously doing research
in just that area. For example, a future research student might be
pursuing the same research and be interested to find out exactly
what you did. ("Why doesn't the widget that Bloggs built for her
project work any more? Where's the circuit diagram? I'll look up
her thesis." "Blow's subroutine doesn't converge in my parameter
space! I'll have to look up his thesis." "How did that group in
Sydney manage to get that technique to work? I'll order a
microfilm of that thesis they cited in their paper.") For
important parts of apparatus, you should include workshop
drawings, circuit diagrams and computer programs, usually as
appendices. (By the way, the intelligible annotation of programs
is about as frequent as porcine aviation, but it is far more
desirable. You wrote that line of code for a reason: at the end of
the line explain what the reason is.) You have probably read the
theses of previous students in the lab where you are now working,
so you probably know the advantages of a clearly explained,
explicit thesis and/or the disadvantages of a vague one.
Make it clear what is yoursIf you use a result,
observation or generalisation that is not your own, you must
usually state where in the scientific literature that result is
reported. The only exceptions are cases where every researcher in
the field already knows it: dynamics equations need not be
followed by a citation of Newton, circuit analysis does not need a
reference to Kirchoff. The importance of this practice in science
is that it allows the reader to verify your starting position.
Physics in particular is said to be a vertical science: results
are built upon results which in turn are built upon results etc.
Good referencing allows us to check the foundations of your
additions to the structure of knowledge in the discipline, or at
least to trace them back to a level which we judge to be reliable.
Good referencing also tells the reader which parts of the thesis
are descriptions of previous knowledge and which parts are your
additions to that knowledge. In a thesis, written for the general
reader who has little familiarity with the literature of the
field, this should be especially clear. It may seem tempting to
leave out a reference in the hope that a reader will think that a
nice idea or an nice bit of analysis is yours. I advise against
this gamble. The reader will probably think: "What a nice idea---I
wonder if it's original?". The reader can probably find out via
the library, the net or even just from a phone call.
If you are writing in the passive voice, you must be more
careful about attribution than if you are writing in the active
voice. "The sample was prepared by heating yttrium..." does not
make it clear whether you did this or whether Acme Yttrium did it.
"I prepared the sample..." is clear.
StyleThe text must be clear. Good grammar and
thoughtful writing will make the thesis easier to read. Scientific
writing has to be a little formal---more formal than this text.
Native English speakers should remember that scientific English is
an international language. Slang and informal writing will be
harder for a non-native speaker to understand.
Short, simple phrases and words are often better than long
ones. Some politicians use "at this point in time" instead of
"now" precisely because it takes longer to convey the same
meaning. They do not care about elegance or efficient
communication. You should. On the other hand, there will be times
when you need a complicated sentence because the idea is
complicated. If your primary statement requires several
qualifications, each of these may need a subordinate clause: "When
[qualification], and where [proviso], and if [condition] then
[statement]". Some lengthy technical words will also be necessary
in many theses, particularly in fields like biochemistry. Do not
sacrifice accuracy for the sake of brevity. "Black is white" is
simple and catchy. An advertising copy writer would love it.
"Objects of very different albedo may be illuminated differently
so as to produce similar reflected spectra" is longer and uses
less common words, but, compared to the former example, it has the
advantage of being true. The longer example would be fine in a
physics thesis because English speaking physicists will not have
trouble with the words. (A physicist who did not know all of those
words would probably be glad to remedy the lacuna either from the
context or by consulting a dictionary.)
Sometimes it is easier to present information and arguments as
a series of numbered points, rather than as one or more long and
awkward paragraphs. A list of points is usually easier to write.
You should be careful not to use this presentation too much: your
thesis must be a connected, convincing argument, not just a list
of facts and observations.
One important stylistic choice is between the active voice and
passive voice. The active voice ("I measured the frequency...") is
simpler, and it makes clear what you did and what was done by
others. The passive voice ("The frequency was measured...") makes
it easier to write ungrammatical or awkward sentences. If you use
the passive voice, be especially wary of dangling participles. For
example, the sentence "After considering all of these possible
materials, plutonium was selected" implicitly attributes
consciousness to plutonium. This choice is a question of taste: I
prefer the active because it is clearer, more logical and makes
attribution simple. The only arguments I have ever heard for
avoiding the active voice in a thesis are (i) many theses are
written in the passive voice, and (ii) some very polite people
find the use of "I" immodest. Use the first person singular, not
plural, when reporting work that you did yourself: the editorial
'we' may suggest that you had help beyond that listed in your
acknowledgments, or it may suggest that you are trying to share
any blame. On the other hand, retain plural verbs for "data":
"data" is the plural of "datum", and lots of scientists like to
preserve the distinction. Just say to yourself "one datum is ..",
"these data are.." several times. An excellent and widely used
reference for English grammar and style is A Dictionary of
Modern English Usage by H.W. Fowler.
PresentationThere is no need for a thesis to be a
masterpiece of desk-top publishing. Your time can be more
productively spent improving the content than the appearance.
In many cases, a reasonably neat diagram can be drawn by hand
faster than with a graphics package, and you can scan it if you
want an electronic version. Either is usually satisfactory. A one
bit (i.e. black and white), moderate resolution scan of a
hand-drawn sketch will be bigger than a line drawing generated on
a graphics package, but not huge. While talking about the size of
files, we should mention that photographs look pretty but take up
a lot of memory. There's another important difference, too. The
photographer thought about the camera angle and the focus etc. The
person who drew the schematic diagram thought about what
components ought to be depicted and the way in which the
components of the system interacted with each other. So the
numerically small information content of the line drawing may be
much more useful information than that in a photograph.
Another note about figures and photographs. In the digital
version of your thesis, do not save ordinary photographs or other
illustrations as bitmaps, because these take up a lot of memory
and are therefore very slow to transfer. Nearly all graphics
packages allow you to save in compressed format as .jpg or .gif
files. Further, you can save space/speed things up by reducing the
number of colours. In vector graphics (as used for drawings),
shades or grey are often produced by black and white pixels, so
one-bit colour is adequate.
In general, students spend too much time on diagrams---time
that could have been spent on examining the arguments, making the
explanations clearer, thinking more about the significance and
checking for errors in the algebra. The reason, of course, is that
drawing is easier than thinking.
I do not think that there is a strong correlation (either way)
between length and quality. There is no need to leave big gaps to
make the thesis thicker. Readers will not appreciate large amounts
of vague or unnecessary text.
Approaching the endA deadline is very useful in some
ways. You must hand in the thesis, even if you think that you need
one more draft of that chapter, or someone else's comments on this
section, or some other refinement. If you do not have a deadline,
or if you are thinking about postponing it, please take note of
this: A thesis is a very large work. It cannot be made perfect
in a finite time. There will inevitably be things in it that
you could have done better. There will be inevitably be some
typos. Indeed, by some law related to Murphy's, you will discover
one when you first flip open the bound copy. No matter how much
you reflect and how many times you proof read it, there will be
some things that could be improved. There is no point hoping that
the examiners will not notice: many examiners feel obliged to find
some examples of improvements (if not outright errors) just to
show how thoroughly they have read it. So set yourself a deadline
and stick to it. Make it as good as you can in that time, and then
hand it in! (In retrospect, there was an advantage in writing a
thesis in the days before word processors, spelling checkers and
typing programs. Students often paid a typist to produce the final
draft and could only afford to do that once.)
How many copies?Talk to your adviser about this. As
well as those for the examiners, the university libraries and
yourself, you should make some distribution copies. These copies
should be sent to other researchers who are working in your field
so that:
- they can discover what marvellous work you have been doing
before it appears in journals;
- they can look up the fine details of methods and results
that will or have been published more briefly elsewhere;
- they can realise what an excellent researcher you are. This
realisation could be useful if a post- doctoral position were
available in their labs. soon after your submission, or if they
were reviewers of your research/post-doctoral proposal. Even
having your name in their bookcases might be an advantage.
Whatever the University's policy on single or double-sided
copies, the distribution copies could be double-sided paper, or
digital, so that forests and postage accounts are not excessively
depleted by the exercise. Your adviser could help you to make up a
list of interested and/or potentially useful people for such a
mailing list. Your adviser might also help by funding the copies
and postage if they are not covered by your scholarship. A CD with
your thesis will be cheaper than a paper copy. You don't have to
burn them all yourself: companies make multiple copies for several
dollars a copy.
The following comment comes from Marilyn Ball of the Australian
National University in Canberra: "When I finished writing my
thesis, a postdoc wisely told me to give a copy to my parents. I
would never have thought of doing that as I just couldn't imagine
what they would do with it. I'm very glad to have taken that
advice as my parents really appreciated receiving a copy and
proudly displayed it for years. (My mother never finished high
school and my father worked with trucks - he fixed 'em, built 'em,
drove 'em, sold 'em and junked 'em. Nevertheless, they enjoyed
having a copy of my thesis.)"
PersonalIn the ideal situation, you will be able to
spend a large part---perhaps a majority---of your time writing
your thesis. This may be bad for your physical and mental health.
- Typing
- Set up your chair and computer properly. The Health Service,
professional keyboard users or perhaps even the school safety
officer will be able to supply charts showing recommended
relative heights, healthy postures and also exercises that you
should do if you spend a lot of time at the keyboard. These last
are worthwhile insurance: you do not want the extra hassle of
back or neck pain. Try to intersperse long sessions of typing
with other tasks, such as reading, drawing, calculating,
thinking or doing research.
If you do not touch type, you should learn to do so for the
sake of your neck as well as for productivity. There are several
good software packages that teach touch typing interactively. If
you use one for say 30 minutes a day for a couple of weeks, you
will be able to touch type. By the time you finish the thesis,
you will be able to touch type quickly and accurately and your
six hour investment will have paid for itself. Be careful not to
use the typing exercises as a displacement activity.
- Exercise
- Do not give up exercise for the interim. Lack of exercise
makes you feel bad, and you do not need anything else making you
feel bad while writing a thesis. 30-60 minutes of exercise per
day is probably not time lost from your thesis: I find that if I
do not get regular exercise, I sleep less soundly and longer.
How about walking to work and home again? (Walk part of the way
if your home is distant.) Many people opine that a walk helps
them think, or clears the head. You may find that an occasional
stroll improves your productivity.
- Food
- Do not forget to eat, and make an effort to eat healthy
food. You should not lose fitness or risk illness at this
critical time. Exercise is good for keeping you appetite at a
healthy level. I know that you have little time for cooking, but
keep a supply of fresh fruit, vegetables and bread. It takes
less time to make a sandwich than to go to the local fast food
outlet, and you will feel better afterwards.
- Drugs
- Thesis writers have a long tradition of using coffee as a
stimulant and alcohol or marijuana as relaxants. (Use of alcohol
and coffee is legal, use of marijuana is not.) Used in
moderation, they do not seem to have ill effects on the quality
of thesis produced. Excesses, however, are obviously
counter-productive: several espressi and you will be buzzing too
much to sit down and work; several drinks at night will slow you
down next day.
- Others
- Other people will be sympathetic, but do not take them for
granted. Spouses, lovers, family and friends should not be
undervalued. Spend some time with them and, when you do, have a
good time. Do not spend your time together complaining about
your thesis: they already resent the thesis because it is
keeping you away from them. If you can find another student
writing a thesis, then you may find it therapeutic to complain
to each other about advisers and difficulties. S/he need not be
in the same discipline as you are.
CodaKeep going---you're nearly there! Most PhDs will
admit that there were times when we thought about reasons for not
finishing. But it would be crazy to give up at the writing stage,
after years of work on the research, and it would be something to
regret for a long time.
Writing a thesis is tough work. One anonymous post doctoral
researcher told me: "You should tell everyone that it's going to
be unpleasant, that it will mess up their lives, that they will
have to give up their friends and their social lives for a while.
It's a tough period for almost every student." She's right: it is
certainly hard work, it will probably be stressful and you will
have to adapt your rhythm to it. It is also an important rite of
passage and the satisfaction you will feel afterwards is
wonderful. On behalf of scholars everywhere, I wish you good luck!
A suggested thesis structure The list of contents and
chapter headings below is appropriate for some theses. In some
cases, one or two of them may be irrelevant. Results and
Discussion are usually combined in several chapters of a thesis.
Think about the plan of chapters and decide what is best to report
your work. Then make a list, in point form, of what will go in
each chapter. Try to make this rather detailed, so that you end up
with a list of points that corresponds to subsections or even to
the paragraphs of your thesis. At this stage, think hard about the
logic of the presentation: within chapters, it is often possible
to present the ideas in different order, and not all arrangements
will be equally easy to follow. If you make a plan of each chapter
and section before you sit down to write, the result will probably
be clearer and easier to read. It will also be easier to write.
- Copyright waiver
- Your institution may have a form for this (UNSW does). In
any case, this standard page gives the university library the
right to publish the work, possibly by microfilm or some other
medium. (At UNSW, the Postgraduate Student Office will give you
a thesis pack with various guide-lines and rules about thesis
format. Make sure that you consult that for its formal
requirements, as well as this rather informal guide.)
- Declaration
- Check the wording required by your institution, and whether
there is a standard form. Many universities require something
like: "I hereby declare that this submission is my own work and
that, to the best of my knowledge and belief, it contains no
material previously published or written by another person nor
material which to a substantial extent has been accepted for the
award of any other degree or diploma of the university or other
institute of higher learning, except where due acknowledgment
has been made in the text. (signature/name/date)"
- Title page
- This may vary among institutions, but as an example:
Title/author/"A thesis submitted for the degree of Doctor of
Philosophy in the Faculty of Science/The University of New South
Wales"/date.
- Abstract
- Of all your thesis, this part will be the most widely
published and most read because it will be published in
Dissertation Abstracts International. It is best written towards
the end, but not at the very last minute because you will
probably need several drafts. It should be a distillation of the
thesis: a concise description of the problem(s) addressed, your
method of solving it/them, your results and conclusions. An
abstract must be self-contained. Usually they do not contain
references. When a reference is necessary, its details should be
included in the text of the abstract. Check the word limit.
- Acknowledgments
- Most thesis authors put in a page of thanks to those who
have helped them in matters scientific, and also indirectly by
providing such essentials as food, education, genes, money,
help, advice, friendship etc. If any of your work is
collaborative, you should make it quite clear who did which
sections.
- Table of contents
- The introduction starts on page 1, the earlier pages should
have roman numerals. It helps to have the subheadings of each
chapter, as well as the chapter titles. Remember that the thesis
may be used as a reference in the lab, so it helps to be able to
find things easily.
- Introduction
- What is the topic and why is it important? State the
problem(s) as simply as you can. Remember that you have been
working on this project for a few years, so you will be very
close to it. Try to step back mentally and take a broader view
of the problem. How does it fit into the broader world of your
discipline?
Especially in the introduction, do not overestimate the
reader's familiarity with your topic. You are writing for
researchers in the general area, but not all of them need be
specialists in your particular topic. It may help to imagine
such a person---think of some researcher whom you might have met
at a conference for your subject, but who was working in a
different area. S/he is intelligent, has the same general
background, but knows little of the literature or tricks that
apply to your particular topic.
The introduction should be interesting. If you bore the
reader here, then you are unlikely to revive his/her interest in
the materials and methods section. For the first paragraph or
two, tradition permits prose that is less dry than the
scientific norm. If want to wax lyrical about your topic, here
is the place to do it. Try to make the reader want to read the
kilogram of A4 that has arrived uninvited on his/her desk. Go to
the library and read several thesis introductions. Did any make
you want to read on? Which ones were boring?
This section might go through several drafts to make it read
well and logically, while keeping it short. For this section, I
think that it is a good idea to ask someone who is not a
specialist to read it and to comment. Is it an adequate
introduction? Is it easy to follow? There is an argument for
writing this section---or least making a major revision of
it---towards the end of the thesis writing. Your introduction
should tell where the thesis is going, and this may become
clearer during the writing.
- Literature review
- Where did the problem come from? What is already known about
this problem? What other methods have been tried to solve it?
Ideally, you will already have much of the hard work done, if
you have been keeping up with the literature as you vowed to do
three years ago, and if you have made notes about important
papers over the years. If you have summarised those papers, then
you have some good starting points for the review.
If you didn't keep your literature notes up to
date, you can still do something useful: pass on the following
advice to any beginning PhD students in your lab and tell them
how useful this would have been to you. When you start reading
about a topic, you should open a spread sheet file, or at least
a word processor file, for your literature review. Of course you
write down the title, authors, year, volume and pages. But you
also write a summary (anything from a couple of sentences to a
couple of pages, depending on the relevance). In other columns
of the spread sheet, you can add key words (your own and theirs)
and comments about its importance, relevance to you and its
quality.
How many papers? How relevant do they have to be before you
include them? Well, that is a matter of judgement. On the order
of a hundred is reasonable, but it will depend on the field. You
are the world expert on the (narrow) topic of your thesis: you
must demonstrate this.
A political point: make sure that you do not omit relevant
papers by researchers who are like to be your examiners, or by
potential employers to whom you might be sending the thesis in
the next year or two.
-
Middle chapters
- In some theses, the middle chapters are the journal articles
of which the student was major author. There are several
disadvantages to this format.
One is that a thesis is both allowed and expected to have
more detail than a journal article. For journal articles, one
usually has to reduce the number of figures. In many cases, all
of the interesting and relevant data can go in the thesis, and
not just those which appeared in the journal. The degree of
experimental detail is usually greater in a thesis. Relatively
often a researcher requests a thesis in order to obtain more
detail about how a study was performed.
Another disadvantage is that your journal articles may have
some common material in the introduction and the "Materials and
Methods" sections.
The exact structure in the middle chapters will vary among
theses. In some theses, it is necessary to establish some
theory, to describe the experimental techniques, then to report
what was done on several different problems or different stages
of the problem, and then finally to present a model or a new
theory based on the new work. For such a thesis, the chapter
headings might be: Theory, Materials and Methods, {first
problem}, {second problem}, {third problem}, {proposed
theory/model} and then the conclusion chapter. For other theses,
it might be appropriate to discuss different techniques in
different chapters, rather than to have a single Materials and
Methods chapter.
Here follow some comments on the elements Materials and
Methods, Theory, Results and discussion which may or may not
correspond to thesis chapters.
- Materials and Methods
- This varies enormously from thesis to thesis, and may be
absent in theoretical theses. It should be possible for a
competent researcher to reproduce exactly what you have done by
following your description. There is a good chance that this
test will be applied: sometime after you have left, another
researcher will want to do a similar experiment either with your
gear, or on a new set-up in a foreign country. Please write for
the benefit of that researcher.
In some theses, particularly multi-disciplinary or
developmental ones, there may be more than one such chapter. In
this case, the different disciplines should be indicated in the
chapter titles.
- Theory
- When you are reporting theoretical work that is not
original, you will usually need to include sufficient material
to allow the reader to understand the arguments used and their
physical bases. Sometimes you will be able to present the theory
ab initio, but you should not reproduce two pages of
algebra that the reader could find in a standard text. Do not
include theory that you are not going to relate to the work you
have done.
When writing this section, concentrate at least as much on
the physical arguments as on the equations. What do the
equations mean? What are the important cases?
When you are reporting your own theoretical work, you must
include rather more detail, but you should consider moving
lengthy derivations to appendices. Think too about the order and
style of presentation: the order in which you did the work may
not be the clearest presentation.
Suspense is not necessary in reporting science: you should
tell the reader where you are going before you start.
- Results and discussion
- The results and discussion are very often combined in
theses. This is sensible because of the length of a thesis: you
may have several chapters of results and, if you wait till they
are all presented before you begin discussion, the reader may
have difficulty remembering what you are talking about. The
division of Results and Discussion material into chapters is
usually best done according to subject matter.
Make sure that you have described the conditions which
obtained for each set of results. What was held constant? What
were the other relevant parameters? Make sure too that you have
used appropriate statistical analyses. Where applicable, show
measurement errors and standard errors on the graphs. Use
appropriate statistical tests.
Take care plotting graphs. The origin and intercepts are
often important so, unless the ranges of your data make it
impractical, the zeros of one or both scales should usually
appear on the graph. You should show error bars on the data,
unless the errors are very small. For single measurements, the
bars should be your best estimate of the experimental errors in
each coordinate. For multiple measurements these should include
the standard error in the data. The errors in different data are
often different, so, where this is the case, regressions and
fits should be weighted (i.e. they should minimize the sum of
squares of the differences weighted inversely as the size of the
errors.) (A common failing in many simple software packages that
draw graphs and do regressions is that they do not treat errors
adequately. UNSW student Mike Johnston has written a plotting
routine that plots data with error bars and performs
weighted least square regressions. It is at
http://www.phys.unsw.edu.au/3rdyearlab/graphing/graph.html). You
can just 'paste' your data into the input and it generates a .ps
file of the graph.
In most cases, your results need discussion. What do they
mean? How do they fit into the existing body of knowledge? Are
they consistent with current theories? Do they give new
insights? Do they suggest new theories or mechanisms?
Try to distance yourself from your usual perspective and look
at your work. Do not just ask yourself what it means in terms of
the orthodoxy of your own research group, but also how other
people in the field might see it. Does it have any implications
that do not relate to the questions that you set out to answer?
-
Final chapter, references and appendices
- Conclusions and suggestions for further work
- Your abstract should include your conclusions in very brief
form, because it must also include some other material. A
summary of conclusions is usually longer than the final section
of the abstract, and you have the space to be more explicit and
more careful with qualifications. You might find it helpful to
put your conclusions in point form.
It is often the case with scientific investigations that more
questions than answers are produced. Does your work suggest any
interesting further avenues? Are there ways in which your work
could be improved by future workers? What are the practical
implications of your work?
This chapter should usually be reasonably short---a few pages
perhaps. As with the introduction, I think that it is a good
idea to ask someone who is not a specialist to read this section
and to comment.
- References (See also under literature review)
- It is tempting to omit the titles of the articles cited, and
the university allows this, but think of all the times when you
have seen a reference in a paper and gone to look it up only to
find that it was not helpful after all.
- Appendices
- If there is material that should be in the thesis but which
would break up the flow or bore the reader unbearably, include
it as an appendix. Some things which are typically included in
appendices are: important and original computer programs, data
files that are too large to be represented simply in the results
chapters, pictures or diagrams of results which are not
important enough to keep in the main text.
- Some sites with related material
How to survive a
thesis defence
Research
resources and links supplied by Deakin University
'Writing and
presenting your thesis or dissertation' by Joseph Levine at
Michigan State University, USA
"Final year projects":
a guide from Mike Hart at King Alfred's College, Winchester,
UK
Postgraduate
Student Resources supplied by University of Canberra
A
useful aid to surviving meetings with
management
The
National Association of Graduate - Professional Students (USA)
- Some relevant texts
Stevens, K. and Asmar, C (1999)
'Doing postgraduate research in Australia'. Melbourne University
Press, Melbourne ISBN 0 522 84880 X.
Phillips, E.M and Pugh,
D.S. (1994) 'How to get a PhD : a handbook for students and their
supervisors'. Open University Press, Buckingham, England
Tufte, E.R. (1983) 'The visual display of quantitative
information'. Graphics Press, Cheshire, Conn.
Tufte, E.R.
(1990) 'Envisioning information' Graphics Press, Cheshire, Conn.
Distribution
If you have found these documents useful,
please feel free to pass the address or a hard copy to any other
thesis writers or graduate student organisations. Please do not
sell them, or use any of the contents without acknowledgement.
Suggestions, thanks and caveats
This document will be
updated occasionally. If you have suggestions for inclusions,
amendments or other improvements, please send them. Do so after
you have submitted the thesis---do not use this invitation as a
displacement activity. I thank Marilyn Ball, Gary Bryant, Bill
Whiten and J. Douglas, whose suggestions have been incorporated in
this version. Substantial contributions will be acknowledged in
future versions. I also take this opportunity to thank my own
thesis advisers, Stjepan Marcelja and Jacob Israelachvili, for
their help and friendship, and to thank the graduate students to
whom I have had the pleasure to be an adviser, a colleague and a
friend. Opinions expressed in these notes are mine and do not
necessarily reflect the policy of the University of New South
Wales or of the School of Physics.
A FAQ and some observations about the web
Why and how
did I write this document? The need for it was evident so, as one
of my PhD students approached the end of his project, I made notes
of everything that I said to him about thesis writing. These notes
became the plan for the first draft of this document, which has
been extended several times since then. I am surprised that it has
several thousand readers each month. However, this is an important
message about the web. It takes time and thought to make a good
resource but, if you do, it can benefit a lot of people. When this
document was first posted, the web was relatively new and feedback
showed that people were often surprised to find what they sought.
Now there is a tendency to take the web for granted: one is almost
disappointed not to find what one is seeking. However, the web is
only as good as the collective effort of all of us. The readers of
this document will be scholars, experts and educators: among the
many contributions you will make to knowledge and your
communities, there may be contributions that should be made freely
available, all over the world. Keep this observation about the web
in the back of your mind for later, when you are not
writing a thesis.
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