Martin's guide to paper grammar
This page summarizes some principles on grammar that I've passed on to
students individually over the past few years.
It is not intended to be a substitute for careful reading or a usage
guide: it just summarizes a few points that are relevant to writing
academic papers in astronomy.
Voice
Verbs in English have two voices: the active and
the passive.
| Active example | Passive example |
|---|
| We analysed the data | The data were analysed |
| Bloggs et al. (2008) showed... | It was shown by
Bloggs et al. (2008).. |
| In this paper we present... | In this paper ... is
presented |
Using the passive voice de-emphasises the person or thing who
did what you're describing. In some cases, as in example (1) above, it
makes it unclear who actually carried out the action that's being
described. It used to be the case that people were advised to write
scientific papers largely in the passive voice. While I don't think
you need to try to avoid it altogether (sometimes it's useful, as in
the previous sentence) I feel strongly that you should write in
the active voice when you are describing what you or we have
done in a paper. I.e., we analysed the data, not the data
were analysed; we show that... not it is shown
that.... Using the passive here is at best cumbersome and at
worst actually makes it unclear who did what.
Pronouns
If you are writing a multi-author paper, use 'we' and 'us'. If you are
writing a single-author paper (or a thesis!), possible strategies include
- Using 'we' and 'us' anyway (but this makes you look like you think
you're the Queen)
- Using the passive throughout (bad, see above)
- Using 'I' and 'me'.
I prefer the third option but opinion is split.
Note that you are allowed to use 'we' about papers which do not have
the same set of authors, so long as there is some overlap. (In
Smith & Jones (2005) we showed... is OK as long as
the current authors include either Smith or Jones.)
Referring to papers
Papers are people. That is, when you cite a paper, you are referring
to people who have written a paper, not to a paper written by some
people. Smith & Jones (2005)... is shorthand for Smith and
Jones, in their paper published in 2005, .... Some examples of
the difference this makes:
| Wrong | Right |
|---|
| the data presented in Smith & Jones (2005) | The
data presented by Smith & Jones (2005) |
| It was shown in Bloggs et al. (2008) that | Bloggs et al.
(2008) showed that |
Tenses
This is a very confused area. To start with, I'll introduce the main
tenses used in academic writing.
Present tense
This describes an action that is happening now or a fact which is
independent of time.
| Example | Comment |
|---|
| In this paper we present | We are presenting it right
now |
| Centaurus A is a strongly variable X-ray
source | Fact |
Simple past tense (preterite)
This describes an action that happened in the past, or something that
was true but may now not be, or any assertion about the past that
comes with a past date or time associated with it.
| Example | Comment |
|---|
| We processed the data in the standard manner. | Took
place in the past |
| Centaurus A varied strongly between 2003 and
2007. | Statement about past facts, date in past |
Perfect tense
This describes the state of things now as a result of an event that
took place in the past. (An important consequence of this is that
statements in the perfect tense can't have times in the past
associated with them. I have been to Paris is a statement about
my state now as a result of having been to Paris in the past. *I
have been to Paris in 2008 is ungrammatical because it refers
to a specific past event. Native speakers of languages that lack a
true perfect tense need to learn this rule.)
In scientific writing, we use the perfect to make statements about
past events that affect us at the time of writing.
| Example | Comment |
|---|
| We have previously shown that... | ... and so now we are
able to do something with that result. |
| In their earlier work Bloggs et al. have
argued | Sets the scene for what we're saying now |
The use of the perfect flags up the fact that these past events are
relevant to the present discussion.
Future tense
Fairly obvious; formed with 'will' and 'shall'. (The rule that 'shall'
is the non-emphatic first-person future is more or less dead, but you
should feel free to use it if you like.)
What tenses should you use?
Basically use any you like, as long as they are coherent (make sense)
and consistent (follow some logical rule which you obey throughout the
paper). Consistency is usually the problem: for example, a very common
error is to oscillate between the present and preterite
tenses in describing the work you've done in the paper. Here's my
suggestion for a logical scheme for a standard data + interpretation
paper, though.
Abstract
Use the present tense when describing the work you are doing
now. (In this paper we present... we show that... we argue. Use
the preterite for facts about the past that you need to
introduce (Cen A was strongly variable during our
observations). Use the perfect for any retrospectives on
your or other people's work that you need to give (note that it is not
usually a good idea to cite papers, yours or others', in an abstract).
Introduction
Use whatever combination of tenses is appropriate to describe earlier
work, but use the present (in particular, not
the future) tense, as for the abstract, in describing any new
work you are doing in the paper being written.
Analysis and discussion
When describing your data analysis, processing, calculations,
simulations etc. use the preterite. From the perspective of the
writing of the paper, you are describing events that happened in the
past. (We processed... we used the AIPS software package to image...
we fitted a Gaussian... we carried out a K-S test....) Use
the present to describe something you are doing as you
write: We conclude that... We prefer an interpretation in
which.... Remember that the paper is written from the idealized
perspective in which you have done all the work before you start
writing!
Please note that the preterite form of 'fit' is 'fitted'.
Summary and conclusions
When reviewing discussion that took place earlier in the paper, it may
be appropriate to use the perfect or the preterite
(We have argued that... In Section 5 we found...). However, a
statement of the paper's conclusions should be in the present.
Punctuation
The most common error here is to use a comma to separate connected
sentences:
We were unable to solve the problem by doing X, it was necessary to do
Y.
This is wrong in formal English. Sentences must either be joined by a
connecting word (and, but...) or by a semicolon ;, or they must be
separated by a full stop. The semicolon should be used whenever you
want to indicate that two sentences are connected without using some
explicit word to connect them. That word may not be at the join
between sentences! For example,
Since we were unable to solve the problem by doing X, it was necessary to do
Y.
is fine.
Note a special rule for the connecting word 'however':
| Example | Comment |
|---|
| When we did X we obtained result Y, however when we did P we
found Q | Wrong |
| When we did X we obtained result Y; however, when we did P we
found Q | Right |
'However' as a connective always starts a new sentence; it must be
preceded by a semicolon and followed by a comma.
Prepositions
Try to avoid leaving these at the end of a sentence if you can, in
formal writing: prefer 'the data from which we extracted the spectrum'
to 'the data we extracted the spectrum from'.
that
In formal English you should generally use 'that' wherever it can be
used to introduce a dependent clause: so
| Example | Comment |
|---|
| We observed the target was variable | Wrong |
| We observed that the target was variable | Right |