How to write a technical or scientific report

Version 2.02, December 2024

Summary

This article is about writing a technical report or scientific paper. In it, I describe the conventional 'standard model' of report writing, and some possible alternatives. I wrote this article for students who are currently undertaking undergraduate or master's degree projects, or expect to do so in the near future. However, some parts will be relevant to people who write in the course of business.

When I first wrote this article, back in the mid-1990s, we still presented most reports and scientific papers in printed form. These days, web-based publishing is commonplace, even for prestigious scientific journals. I've encountered the view that it's OK for web-based articles to be rushed and crude, that they don't have to reach the same authorial standards that apply to print. I would argue that the opposite is the case -- there is so much material on the web, both reliable and unreliable, that a high standard of clarity and organization is more important there than in print. There's just too much online, to force ourselves to read things that are disorganized or stylistically jarring.

Please note that I'm writing primarily for a British readership. Some of what follows may be relevant in other English-speaking countries, but I can't be sure.

Summary
Contents
1 Introduction
2 Fundamentals
3 The standard model
4 Alternatives to the standard model
5 Language, style and presentation
6 Graphic material
7 Things to avoid
8 General guidelines
Bibliography

1 Introduction

The ability to write clear, concise reports is an asset to almost any professional. In this article I offer some general guidelines on report writing, focusing particularly on something I call the 'standard model'. This standard model is a formalization of the way we have typically written scientific and technical articles over the last seventy years or so. While the standard model has its faults, and some writers use it inappropriately, it still has a lot to recommend it. I normally suggest to students who don't have much writing experience that they follow this model unless they have good reasons not to. In this article I also try to explain why we teach students to write in a particular way.

2 Fundamentals

The main purpose of a scientific or technical report is to convey information. The report should place as few hindrances as possible between the minds of the writer and the reader. A secondary function is to stimulate and entertain. There are people -- a tiny minority -- who can inform and entertain at the same time. If, like most people, you have to make a choice between the two, you should try to inform rather than to entertain. Of course, if you're writing a novel or a screenplay the priorities are different; but in technical writing clarity of information is paramount.

A good report needs careful planning. As part of the planning stage you should try to answer the following questions.

First, what is the report about? What are you trying to say? You should arrange material so that key facts and conclusions are early and accessible. Not everyone will read the whole report, so ensure that your message will get across even if a reader only skims it. Many people have an attention span of only a few minutes, when reading something they aren't immediately captivated by.

Who are you writing for? It is impossible to write a technical document that will be equally easy for everybody to read, regardless of expertise. It is essential to identify the potential readers -- the professional group, if not the individuals -- before you start writing. You should keep in mind that you probably know more about your subject than your readers do. If you are writing for computer scientists, for example, you probably don't need to explain what software is, nor the World-Wide Web, but you might need to explain how phase modulation works, or what JMS stands for.

How long can the report be? You should be able to decide as a minimum whether you expect to write 2 000 words or 20 000 words, for example. It's generally harder to write a short report than a long one, because it requires much better organisation. In the academic environment there may be institutional limitations on the size of the report.

3 The standard model

The 'standard model' of report writing is a style and structure we've used widely in the western world for about seventy years. It is the reporting method that we usually teach (sometimes badly) in schools. Contrary to what we learned in school, however, it is not the only accepted way to write professionally. Nevertheless, it is the way that many scientists and engineers choose to write. The main elements of a 'standard model' report are as follows.

There's an abstract that sums up the entire report.
The first major section is an introduction; the last is a conclusion. The conclusion answers questions posed -- explicitly or otherwise -- in the introduction.
Factual material and measurements are completely separate from opinion and interpretation, often in different chapters or sections.
Formal, and rather impersonal, language is used (often too much).
The report usually refers extensively to the work of others.
The sections of the report are often numbered.

Most 'standard model' reports will contain some or all of the following sections, usually in this order. I'll discuss sach of these sections in more detail below.

Abstract or summary; Acknowledgements; Introduction; Objectives; Theory; Method (or methodology or procedure); Results; Discussion or interpretation; Conclusions; Recommendations; References and/or bibliography; Appendices.

A standard report, if it is more than a few pages long, will probably also contain a table of contents, a list of abbreviations and technical terms, and perhaps an index if it is very long.

3.1 The abstract or summary

An 'abstract' or 'summary' (these words mean essentially the same thing) contains a brief overview of the report, including its conclusions and recommendations if there are any. A good length for an abstract is about 300 words: many scientific journals specify this word count explicitly. The abstract of a scientific paper or report should be capable of standing alone, and of being published separately. For this reason we don't usually include the abstract in the report's numbering scheme.

3.2 The introduction section

The introduction states what the report is about, and its relationship to other work in the field. If the report is about experimental work, the introduction will often summarise other, related experiments, and show how the new work extends or supersedes earlier studies. If the report is about development (of software or a product, for example) the introduction typically sets out the purpose of the development, who will benefit, and how it will be used. A report that is a review of existing work will usually just state its scope, purpose, and intended readership.

My preference in scientific writing is to finish the introduction with a list of questions that the project set out to answer. I would then give the answers to these questions in the 'conclusion' section. I like to be quite explicit about this, and sometimes even label the questions 'Question 1', 'Question 2', and so on. Whether you do this or not, the reader should be able to look at the conclusion of your report, and verify that you have indeed found out what you claimed you would find out.

3.3 The objectives section

This section, if present, states what you expected the work to achieve, why you undertook it, and at whose instigation. I usually prefer to put this information in the introduction, but this is just a matter of taste.

3.4 The acknowledgements section

It is polite to give a brief note of thanks to those people who have helped directly in the work the report describes. In a novel, authors often thank their friends and family; I consider it pretentious to do this in a technical report, unless you actually regard them as co-workers.

If the report describes work supported by grant funding, the funding body may insist that it be acknowledged.

It is not uncommon to see acknowledgements at the end of a report, rather than the beginning.

3.5 The theory section

The theory section, if used, describes any technical or mathematical background that a reader should know, to be able understand the report. You probably don't need to explain the properties of logarithms, but you probably will need to explain the principles of calculus of variations, if that's something you use in your analysis. In the end, the amount of theory you need to explicate depends on your readership.

If the theory is so extensive that it might have to be studied rather than just skimmed, it's probably better to place it in an appendix. If you do that it's still helpful, in my view, to provide a brief outline in the body of the report.

3.6 The methods (method, methodology) section

In the 'methods' section you should describe how you carried out the work, what equipment you used, how you collected data, and any particular methodological problems (not personal or financial problems) you had to overcome. If the report is describing a survey -- common in the social sciences -- you should say how you chose your subjects, how you checked for bias, and how you analysed the results. If you used commercial computer software, custom dictates that you should state who supplied it, even when it is obvious or irrelevant.

3.7 The results section

In the standard model, we usually state results as plainly as possible, without any comment or analysis. It is often difficult to know how much raw data to put into this section. My view is that you should include enough data to enable to reader to be confident that you have done what you said you would do, so your conclusions are trustworthy. This certainly does not mean that you should include reams of print-outs or copies of questionnaire returns. I try to summarise the results into a few tables and graphs.

If you really need to include a large volume of results -- and sometimes a conclusion will not be defensible without doing this -- then it might be more useful to place them in an appendix, and include only an outline in the body of the report.

Most readers who are used to reading scientific reports will become uncomfortable if you call a section 'results' and put anything in it apart from plain, uninterpreted results.

3.8 The discussion section

This section provides your interpretation of your results, compares them with other published findings -- if there are any -- and points out any potential shortcomings in the work. As the author, you are allowed (perhaps expected) to be less objective in this section than elsewhere: you may state opinions, and speculate about the significance of the results.

If your findings are unexpected, or very much at odds with established views, you should explain why this might be the case, or the reader will probably assume you just made a mistake. If your findings are at odds with established views, and you don't know why, you should admit that, rather than just ignoring the situation.

3.9 The conclusions section

The conclusions section states the overall findings of the work, as you interpret them. It is important to realise that 'conclusion' does not just mean 'the last bit of the report'. Your conclusions must be definitive statements that a reader can safely conclude from the work. A conclusion is not a summary (you can include a summary as well, if you like). When I examine students' reports, one of the questions I ask is: do the conclusions follow from the body of the report?

3.10 The recommendations section

In this section you may give any advice that you think follows from the conclusions. If the report is about making some sort of business decision, you should offer your suggested course of action here. Some writers use the recommendations sections for suggestions for further work, which seems reasonable to me.

3.11 The references and bibliography

The purpose of citing references is to allow the reader to follow up your sources of supporting information, and thus to ensure that the conclusions you draw really follow from your work and those sources. After all, in science and technology we're ususually extending an existing body of knowledge, not starting from scratch. References are not, as many students appear to think, a method for convincing an examiner that you have read a lot. You should cite references in enough detail that a reader could actually find your sources, even if most readers won't actually do so. For books, we conventionally give the authors, year, edition (if there's more than one), publisher's name and publisher's location, and page numbers. In reality, an ISBN number is sufficient to locate a book, but it's polite to give more information. For articles in journals, give the authors, year, name of the publication, volume and page numbers. If you can't give all these details, you probably don't have a proper reference.

The rise in web-based publishing has created its own citation problems. The same basic principle applies, however: the citation must be sufficient to allow a reader to locate the source of your information. If possible, you should cite a URL that will take the reader directly to the document you cite. Giving the URL for a website is generally not helpful. As a matter of style, you should give the names of the authors and the publication date, if you are able to determine them. If you can't, then a reference to a web page probably won't carry a lot of weight.

Although it is not peculiar to web-based publication, you should be aware that not all citations have equal weight. References to articles in peer-reviewed journals will be more convincing than references to non-reviewed sources, particularly self-published ones. Since anyone can publish anything on a web site, there is a real risk of citing something that is not authoritative. In academic circles, references to Wikipedia and similar sites, although often invaluable for research, usually have no authority whatsoever, for better or worse.

Many students confuse 'references' with 'bibliography'. A bibliography is the set of publications to which you referred in a general sense while writing the report or carrying out the work it describes. These publications will not usually be cited explicitly in the text. References, on the other hand, are given in support of some specific assertion, so you will have mentioned them explicitly in the text. Normally the citation is given after the statement the author wants to support. A common method is to give the authors and year in the text, e.g, (Bloggs, 1995), and the full details at the end of the report or in a footnote.

In scientific writing, if you make any statement that is not one of plain fact or measurement, you must justify it using your own reasoning, or refer the reader to another publication that justifies it. The making of unjustified assertions is probably the single most common criticism leveled at students' writing.

If you use another person's words directly, you must be clear that you're doing this, and give a full reference to the original text. If you use more than a few words, or a picture, or experimental results, you should seek the author's permission first, and state in your report that you obtained such permission. If you don't do this you're potentially breaking the law, as well as being unprofessional.

3.12 The appendices

You should include as appendices information that would break up the flow of the report, and which you don't expect everybody to read. I typically use appendices for mathematical proofs, electrical circuit diagrams and sections of computer programs.

3.13 Numbering and structure

It is common to number each section of the report. Usually numbering starts at the introduction, which has number '1', and continues until the 'references' section. Because they are, in a sense, independent of the body of the report, the abstract and references section are not usually numbered. Most writers number sub-sections as well as main sections. So, for example, section one, sub-section two would be numbered '1.2'. Others prefer numbers and letters, e.g., 1A, 1B..., which is also fine. The advantage of using a hierarchical numbering scheme is that it helps to orient the reader in the report.

3.14 When should you use the standard model?

In my opinion, writers of technical reports should use something close to this standard model, unless there is a sound reason not to. Why? First, and most important, its use is so widespread that the reader will know exactly what to expect in each section. Even people who are not familiar with this type of report will find the clear section divisions useful. Second, the rigid organisation of the report will help the novice writer organise his or her thoughts when writing.

There are times when the standard model will be a hindrance, rather than a help. In such cases you should cheerfully abandon it. Even when you do use the standard model, you won't always need to include every sections. A 'results' section, for example, is only useful if you're actually reporting results or measurements.

4 Alternatives to the standard model

Here are a few suggestions for other ways to organise a technical report, all of which I've seen used successfully.

4.1 The 'segmented' standard model

If a report describes a set of investigations with a common purpose, but different methodologies, it can be rather difficult to use the standard model, even if each individual investigation could be reported that way. In this case it is useful to give each experiment its own segment with a 'methods' and 'results' section, but a single overall introduction and discussion. In the segments, you do not necessarily need to use explicit sub-sections for methods and results, as long as the reader is clear where the boundaries are.

4.2 The 'assertion' model

Assertion-based organization can be very effective when used appropriately, but it's more common in presentations than in written reports. In this type of writing, rather than using generic section titles like 'Introduction', you'd use assertive, explanatory headings, like 'The new protocol improves communication efficiency by 23%'. The headings together make up a summary of the report. Of course, if you make an assertion you then have to go on to defend it, and that defence will form the body of each section. The advantage of this type of writing is that the reader can get an overall idea what the report says simply by scanning the headings. A valid criticism of the standard model is that the reader can't extract any information merely by skimming the headings, as they are non-informative.

4.3 The 'conclusion first' model

In this type of report, the writer presents the conclusions towards the beginning, perhaps directly after the introduction. In my opinion one should re-state or summarise the conclusions at the end of the report as well, otherwise the report ends abruptly. The advantage of placing the conclusions at the beginning is that they are more likely to be read. This organization also allows the reader to have the conclusions in mind while reading the rest of the report. I don't use this kind of writing myself: I prefer to put a summary of the conclusions in the abstract.

4.4 The 'topic' model

In this type of report, each section is on a particular topic or subject, but there will probably be a common introduction and conclusion. This structure is appropriate for review or instructional articles, but probably not so much for scientific papers. The problem is that it does not aid in establishing the clear divisions between methodology, results, and interpretation that most readers will expect.

5 Language, style and presentation

If your message is one of profound importance, readers will absorb it even if you present it badly. On the whole, however, few scientific and technical reports contain ground-breaking findings, and you'll need to pay attention to the presentation.

5.1 Grammar and spelling

Most academics and scientists, and many businesspeople, are fussy about grammar and spelling. If reading forms a substantial part of your work, after all, you'll be most productive if everyone follows similar standards of grammar and spelling. If you want to avoid alienating or inconveniencing your readers, you need your grammar and spelling to be impeccable.

If they aren't especially good, and particularly if you're not working in your native language, it's vital that you have your work read by someone else before you decide that it's finished (I think that everyone should do this anyway). At the very least you should get a printed copy of your document (not on a computer screen) and check it very thoroughly yourself, word by word. Many of us, including me, have become adept at skimming over our own errors without even spotting them, which makes the process of personal proof-reading rather unproductive. Enlisting help here is very much worthwhile.

Most readers won't care whether you use British or American spelling and word choices -- increasingly we are unable to tell the difference, anyway. However, my experience is that many readers have a sharp eye for inconsistency -- if you write 'color' on one line, and 'colour' on the next, it might diminish your credibility.

5.2 Style

Most technical documents are written in a rather formal style. Some readers become disgruntled when they have to read reports that are written informally, but I don't mind this. However, what does annoy me as a reader is sudden changes from formal to informal writing -- it gives the impression that the writing wasn't planned properly.

In the UK, 'passive voice' expressions have long dominated academic writing, as authors struggle to avoid using the word 'I'. Personally, I use the word 'I' freely even in my most formal writing, and I encourage others to do likewise. If you prefer not to, that's fine, but you should try to avoid writing very ugly phrases and clichés just to avoid the word 'I'. For example, a phrase I see all the time in scientific articles is 'It is the opinion of the author that...' This means exactly the same as 'I believe...' but has four times as many words. Lawyers tend to write 'It is submitted that...' to mean the same thing. The worst affront of this type is the double passive: "It is regretted that further data was unable to be collected from this subject." What the author meant was: "Unfortunately, we could not collect more data from this subject". Authors must make up their own minds about the good points and bad points of different styles, but should do so after careful consideration, rather than according to dogma.

We probably overuse passive-voice expressions because we're trying to give an impression of impartiality -- a characteristic we expect of scientists. I don't think many readers will be fooled into thinking that, just because you use the passive voice, you actually are impartial, but that's just my opinion.

In general, I think appropriate humour is fine in a technical report. But if your report is about, say, detection of bowel cancers, what sort of humour is likely to be appropriate? Feeble jokes could detract badly from the message you want to convey. Nevertheless, occasionally humour works.

On the whole you should probably not write in the exact way you speak, for two reasons. First, you probably use colloquial and ungrammatical expressions in your speech, that some readers will not understand. A reader cannot stop you and ask you to clarify. Second, in writing you don't have access to the emphasis and tone of voice that modulates spoken communication. As you have to rely entirely on the words themselves, you'll need to choose them with care.

Have said that, I confess that I prefer to read colloquial speech idioms, over a stuffy, affected academic style.

One final point on style: I think that many principles of good general writing apply equally to report writing. Maxims like "prefer verbs to nouns", "prefer the specific to the general", and "minimize modifiers" apply to all kinds of writing. I won't go into more details here, because these guidelines are well-documented elsewhere. Just be aware that there's nothing about scientific writing that demands ungainly, over-generalized prose with no verbs except "is".

5.3 Presentation

I suggest -- with some hesitation -- that in science, good visual presentation is less important than sound technical content. However, that doesn't mean it is irrelevant: the first impression your report makes on a reader will likely be created by its visual style.

With modern computer software, it is relatively easy for anybody to prepare elegant printed documents and web pages. Even complex mathematics can be typeset stylishly using tools like LaTeX, using nothing more than a PC. The ubiquitous word processor does not much help with consistency, however. A document is consistent if, for example, it always uses the same typeface for headings, if all lines have the same spacing, if all pictures are aligned similarly on the page, and so on. A simple way to ensure consistency is to print the document and have it looked at by an impartial, critical person. Even for on-line publication, I think there's something to be said for reviewing a printed copy, although I appreciate that we have to conserve trees.

The final part of the preparation of a printed report is usually binding. It doesn't cost very much to have a report spiral-bound, and it will be much easier to read than if it is stapled or ring-bound. Hot glue binding can be very effective (and cheap) for thin documents. Unless there are rules to the contrary, it is probably not worth the effort and expense of hard binding a report. I like to receive reports that are glue-bound or spiral-bound in plastic covers, so I can read them in the bathtub without getting wet fingerprints on the pages.

5.4 Inclusivity

Issues of inclusivity now affect all writers and, while I can advise sensitivity in this area, it's hard to give general advice. It's all too easy, particularly in science and engineering, to write in a way that subtly excludes or diminishes particular groups of people. The days are long gone when we could write "he" and "him", and assume that the reader would understand that these terms included the other half of the human race as well.

We won't solve this problem, unfortunately, by simply avoiding overtly gender-laden terms. Particular modes of expression are so entrenched in some industries that we no longer really notice that they might be problematic. A female colleague recently suggested that a woman would not have started using terms like "terminate" or "abort" to mean "stop a computer program". Maybe so; perhaps widespread use of such terms does subliminally "masculinize" the computing industry, particularly when they are ubiquitous.

Similarly, institutional and editorial standards increasingly encourage us to avoid terms that seem tacitly to legitimize slavery and racism. Such standards discourage terms like "master", for example -- a word which has among its many meanings some that are not remotely associated with slavery. Perhaps a term like "blacklist", in the sense of "to exclude", has racist overtones; this is a term that I have used many times, without really being aware of this possibility. I now avoid using it, although the alternatives are inelegant.

The problem that every writer has to tackle here is that of finding balance. Of course we need to avoid derogatory and discriminatory terms in professional writing, but it's increasingly difficult to write in a way that we can be certain will cause no offence to anybody at all. I've been criticised for using the phrase "bring home the bacon" in a training manual. Some religious groups do not eat bacon and, I was told, "normalizing" the eating of bacon can be seen as exclusionary. As a vegetarian, I don't eat bacon either, but it doesn't offend me to see the word in print. Sadly, avoiding every possible way in which we might inadvertently give offence leads to very bland writing.

I've been writing professionally for decades, but I have to confess that I don't have a solution to this problem, and it gets more acute every year. Being aware of the potential problems is a start, but only a start.

6 Graphic material

Few technical reports consist only of text. Here are a few hints on including graphical material, which I concede that many readers will find obvious.

Label everything. All charts and graphs should have a caption and perhaps a number ('Figure 1'). It's no good writing "In the figure below..." unless you have complete control over the document's layout. Check that, when you refer to figures in the text, the references are correct. You might add or remove figures, then forget to update all the cross-references. If you use document-preparation software that has support for automatic cross-reference management, consider using it.

If you prepare graphs in colour, then print them on a monochrome printer, they may become unreadable. For example, it may be impossible to distinguish between a line that was originally back and one that was blue. Some computer software automatically converts coloured graphs to use dotted and dashed lines on a monochrome printer, but most does not. It's a good idea to keep this problem in mind even for web-based publishing, because web browsers sometimes allow the user to control colour rendering.

Film photographs do not usually photocopy very well. For a printed document, you may need to get extra prints made of photographs so that you can include prints with each copy of the report. To be fair, film photography is now used only in specialized applications.

Unlike in an advertising or promotional brochure, colour presentation is not usually worth the extra effort in a printed technical document (except in certain subjects, like computer graphics and multimedia). Even now, many scientific journals do not print in colour, or will only do so if given a financial incentive. It's worth checking this before starting work on the report.

Computer software that is designed for producing slide presentations will often not use sensible type sizes when drawing diagrams for printing on paper. A good size for text labels on a diagram in print is 12-14 points, and the diagram should be scaled accordingly.

7 Things to avoid

Here, in no particular order, are some suggestions of things to avoid in a technical or scientific report. Please note that I am not saying they should be avoided in all types of writing; but a technical report has a particular function and audience, and the writing should reflect this. Naturally, this section describes things that I particularly dislike.

Avoid clichés and stock phrases if you can. Clichés are phrases that seemed elegant or stylish in the past, but are now so over-used that they annoy the reader. Your reader is quite likely to have seen the same cliché used several times that same day. Here are some particularly common examples: 'At the end of the day...', '...explore every avenue', 'Not to put too fine a point on it...', 'Going forward, we will...' The late Terry Pratchett defended Clichés as the "grease on the axles of communication". Maybe they are; but too much grease leads to a sticky mess.
Stock phrases are slightly different from clichés; they're used not because they scan well, but because we get so used to reading them that we feel a subliminal pressure to write them. Particular examples include 'At this point in time...', and 'In the opinion of the author...' You might be able to replace these phrases with a single word. For example 'At this point in time...' can usefully be replaced by 'Now...'.
Some people use stock phrases because they don't have anything else to say; it's best to find something to say starting to say it.

Avoid giving too much raw data. I suspect that some writers overload a report with data for the same reason that others employ useless stock phrases: they don't have much to say. I favour including only a summary of experimental data in a report.

Avoid poems, quotations, and other non-technical material unless there is a very clear need for them. This sort of content is inoffensive when it relates to the subject of the report, but annoying if it does not.

Avoid including program listings and long mathematical proofs if you can. It's unlikely that anyone will want to read them, and anyone who does can ask you for a copy later. If you must include them, put them in an appendix.

It is probably a bad idea to include statements about how difficult the work was, and how the report would have been better if you'd had more time to write it. Students often say this sort of thing in reports and, frankly, it doesn't look very professional.

Try to avoid my usual mistake -- one I've made frequently in this document -- of making everything a bullet-point. A more elegant alternative is to write paragraphs that start with a short heading, that can be emphasised. Bullet-points come from the days of typewriters, when we had no other way to emphasize specific points. It's a habit that I struggle to break.

8 General guidelines

Finally, here are a few general suggestions, in no particular order.

Decide what you want to say, then say it. It's difficult to think about what conclusions to draw from your investigation, while you're writing those conclusions. When you come to write a report, you should be in a position to think only about writing, not about investigation or data interpretation.

Before you write very much, check whether there are standards of authorship to which you must conform. As an undergraduate student, you may find that your institution has rules about how you should present a report. At doctoral level it almost certainly will. Some institutions specify exactly which typefaces to use for various levels of heading, and so on. For journal publication, you'll probably find that you have to provide either camera-ready copy, or plain text with separate figures. 'Camera-ready' means that you provide the finished material, ready to go to the press. You'll have to do all the formatting and layout yourself, according to the journal's rules, and using the journal's preferred software. For most journals, however, you'll be expected to provide plain text -- no layout or formatting -- with the figures on separate pages. I mention this because there's no point spending time getting the flow of text around your figures exactly right, when you'll end up putting them on separate pages.

You don't have to write the report in the same order you expect it to be read. Very often the introduction is the hardest thing to write, as you need to have in mind your conclusions when you write it. A lot of writers start by writing ''1. Introduction'' and then spend a few hours staring at a blank screen. It's perhaps better to write first the parts of the report that deal with methodology and procedures, as no interpretation is involved.

A shorter report is a better report. If you can say the same in 2 000 words as in 5 000, you should. Most people, including myself, tend write too much. Having written a first draft, I can readily remove about 20% of the words with no loss of meaning. Be ruthless: edit your work thoroughly after writing.

People find it hard to be critical of their own work. I suggest that you regard everything you write as a draft, until at least one other person has read it. That other person need not be an expert in the subject; in fact it is often better if you choose someone who is not.

Make all important style and authorship decisions before you start writing. Decide in advance, for example, the degree of balance between formality and informality you prefer, whether you will favour the passive or the active voice, and so on. Having made these decisions, stick to them. If you change your mind, make sure you change the whole report. Major stylistic changes in the middle of a document could annoy the reader.

It's usually better not to edit your document at all until you have written the whole thing to first-draft standard. Yes, I advised ruthless editing earlier; but there's a proper time for that. It's easy to get bogged down in the details of individual sentences, only to find later that you need to remove whole sections.

Writing good reports is difficult, and often takes longer than we anticipate. If possible, allow yourself at least twice as much time as you first think you'll need.

Bibliography

There are many good books on the subject of technical writing, but, in my opinion, none of these are written by or for scientists. The following books are the ones to which I referred when I started teaching.

Burchfield RW (1996) Fowler's modern English usage 3^rd edition (Oxford: Oxford University Press)

King LS (1978) Why not say it clearly? (Boston: Little, Brown and Company)

O'Connor M (1991) Writing successfully in science (London: Chapman Hall)

Of these, O'Connor (1991) is probably the most accessible for beginners, but the style it advocates is a bit stuffy for my taste. I can't be sure that any of these books (apart from Fowler's) are still in print, but in any case you should look for a book that suits your own preference.