some notes by
Joe
Wolfe
What is an honours thesis? For whom is it written? How
should it be written?
In most cases, your thesis is a real research report.
The report concerns a problem in physics and it should describe
what was known about it previously, what you did towards solving
it, and what you think your results mean.
A thesis is not an answer to an assignment question-there
is a big difference. The reader of a student's assignment
is usually the teacher 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 the thesis will not know what the "answer"
is-usually your research project is to discover something
hitherto unknown.
More importantly, one of the readers (the examiner who
is not your adviser) will have at best only a basic idea
of the relevant background, literature etc. Write for that
reader-your adviser will not be too bored while you explain
it: it is always interesting to read something about one's
own field put in different words.
Your thesis will, of course, be read and marked, and then
put away on a shelf in the School library. However it may
also be used seriously in the future as a scientific report,
especially by future research students working on related
projects. Write your report with this audience in mind.
The structure.
The list of chapter headings suggested below may be appropriate
for some theses. In some cases, one or two of them may be
irrelevant. Results and Discussion are often combined in one
chapter. 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.
Once you have a list of chapters and, under each chapter
heading, a list of things to be reported or explained, you
have struck a great blow against writers' block. When you
sit down to type, your aim is no longer a thesis - a somewhat
daunting goal - but something simpler. You will start by
writing the 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 self-confidence. Often the Materials
and Methods is the easiest to write - just write down what
you did.
Abstract.
This 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, your method of solving it, 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
(Jones, P. 1987, J.Abs.Soc. 13, 25).
Introduction.
What is the problem and why is it important? Make the problem
quite clear: and remember that you have been working on this
project for a few months 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 physics? Especially
in the introduction, do not overestimate the reader's familiarity
with your field. Physics is pretty specialised and most of
us are unable to keep pace with developments in all fields.
You are writing for a physicist, but not a specialist. It
may help to imagine such a person - think of some physicist
who knows almost nothing about your field (if your thesis
is in solid state physics, for example, imagine you are trying
to explain it to me). This section 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 sentence or paragraph, 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 slab of A4 that has arrived uninvited
on his/her desk.
Literature review.
Where did the problem come from? What is already known about
this problem? What other methods have been tried to solve
it? This is often a difficult chapter to write: you have only
been in the field for three months and you are trying to review
it! Journal review articles are helpful to give you an idea,
as are the literature review chapters in the Ph.D. theses
of students from the same lab. Unless your thesis is a review
thesis, the review need not be exhaustive, but you will need
to make it clear to the reader that you are familiar with
the state of knowledge in the area of your thesis.
Materials and Methods.
This varies enormously from thesis to thesis, and may be absent
in theoretical theses. The important thing to remember is
that it should be possible for a competent physicist to reproduce
exactly what you have done by following your description.
Theory.
You do 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 need not reproduce 20 pages of algebra that the reader
could find in a standard text.
Concentrate at least as much on the physical arguments
as on the equations! What do the equations mean? What are
the important cases?
Results.
The data often take the form of graphs, though this varies
from thesis to thesis.
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, such as t and chi squared.
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)
Discussion.
What do your results 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?
Conclusions and suggestions for further work.
Well, what did you find? 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? This section should usually be only a page or three.
References.
How many do you need? There are often hundreds of references
in a Ph.D. thesis. The appropriate number in an honours thesis
varies between say several for a highly specific technical
project, to perhaps a hundred in a thesis whose main component
is a literature review.
Appendices (if any).
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. Computer programs are often included as
appendices, as are data files that are too large to be represented
simply in the Results section. (Computer programs should be
intelligibly annotated.) Examiners usually read appendices
only superficially.
General notes:
How much detail?
More than for a scientific paper. Once your thesis has
been marked, and your mum and dad 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 honours project
work any more? Where's the circuit diagram? I'll look up her
thesis." "Nerd's subroutine doesn't converge in
my parameter space! I'll have to look up his thesis.")
It is traditional to include workshop drawings, circuit diagrams
and computer programs, usually as appendices. Ideally, programs
should be intelligibly annotated but this practice is as frequent
as porcine aviation.
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 clear, explicit thesis and/or the disadvantages
of a vague one.
Make it clear what is yours.
If 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 physicist knows it: dynamics equations need
not precede a citation of Newton, circuit analysis doesn't
need a reference to Kirchoff. The importance of this practice
in science is that it allows the reader to verify your starting
position. Physics is said to be a vertical science: results
are built upon results which in turn are built upon results...
Good referencing allows us to check the foundations of your
additions to the structure of physics, 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 the non-specialist 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?". If the reader has
to spend a few hours in the library to find out, then s/he
may not be in a great mood to read the rest of the thesis.
The work that is actually yours may be only a small part
of the whole thesis, especially in a non-numerical theoretical
thesis. Do not feel bad about this: all of us who work in
science know that one has to do a lot of work just to get
to the boundary between the known and the unknown, and that
any small advancement of that boundary is an important achievement.
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.
Presentation.
It must be easy to read, so typing is preferable to handwriting.
There is no need, however, for the finished product 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. Either is satisfactory.
Don't waste time on fancy drawings - fix up the arguments!
Make the explanations clearer! Think more about the significance!
Check for errors in the algebra!
There is no strong correlation (either way) between length
and mark. Readers will not appreciate large amounts of vague
or unnecessary text. There is no need to leave big gaps
and empty pages to make it thicker.
The 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.
One important 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. Unless you are schizophrenic or a queen,
use the first person singular, not plural. 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" attributes
consciousness to Pu. The advantages claimed for writing
in the passive voice is that some other scientists have
done so, and that some very polite people do not like using
the first person pronouns.
Personal.
In 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.
Motivation. The difference between Hons I and Hons
IIa, or between Hons IIa and Hons IIb is substantial. If
you integrate over the following decade the effect of this
difference on your career, it is even more substantial.
If extra work put into your thesis (and course work) takes
you from one category to another, then that work is very
well compensated. It will be hard work, but it's worth it.
Typing. Set up your chair and computer in the recommended
way. The Health Service, departmental typists or perhaps
even the safety officer will be able to supply charts showing
healthy postures and also exercises that you should do after
spending a day at the keyboard. The latter are worthwhile
insurance: you don't want to be crippled by back or shoulder
pain. Try to intersperse long sessions of typing with other
tasks.
Exercise. Don't give up exercise for the interim.
You know that lack of exercise makes you feel bad, and you
don't 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 don't get
regular exercise, I sleep less soundly and longer. How about
walking to work and home again? (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 the occasional
perambulation improves your productivity.
Food. Don't forget to eat, and make an effort to
eat healthy food. You shouldn't let your body fall apart,
or risk illness at this critical time. Exercise is good
for keeping up the appetite. I know that you haven't the
time to cook much, but get a supply of fresh fruit, vegetables
and bread. It takes less time to make a sandwich than to
go to the local fast food, and you'll feel better afterwards.
Drugs. Thesis writers have a long tradition of using
coffee as a stimulant and alcohol or marijuana as relaxants.
(Alcohol and coffee are legal, marijuana is not.) In moderation
they doesn't seem to have ill effects on the quality of
thesis produced. Excesses however are obviously counter-productive:
several short blacks and you will be buzzing too much to
sit down and work; several drinks at night will slow you
down next day.
Other people will be sympathetic, but don't take
them for granted. Spouses, lovers, family and friends shouldn't
be undervalued. Spend some time with them and, when you
do, have a good time. Don't spend your time together complaining
about your thesis: they already resent the thesis because
it is keeping you away from them.
Finally, we all know that writing a thesis is tough work.
It is also a scientific rite of passage, and your colleagues
and teachers will sympathize. Good luck with it!
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.
Joe
Wolfe / J.Wolfe@unsw.edu.au/
61-2-9385 4954 (UT + 10, +11 Oct-Mar)
- Some sites with related material
How to write a PhD thesis.
How to survive a thesis defence
Research
resources and links supplied by Deakin University
Learning
Resources for University Students supplied by Universities
of Western Sydney and Melbourne.
"Writing
and presenting your thesis or dissertation" by
Joseph Levine at Michigan State University, USA
"Postgraduate
Student Resources" supplied by University of Canberra
Tufte, E.R. (1983) 'The visual display of quantitative information'.
Graphics Press, Cheshire, Conn.
Tufte, E.R. (1990) 'Envisioning information' Graphics Press,
Cheshire, Conn.
