Assume that your results show trends or movements over time, such as nicotine concentration in plasma after smoking, a good way to display your data would be to construct a line graph. But do not rely on the computer to design it for you. Here are some common errors.

The line graph

This seemingly excellent line graph nevertheless appears to have two common defects: the curves are distinguished both by type of line and by type of data-point symbol – either would suffice; and the curves are identified by a separate key, obliging the reader to scan back and forth to the key to see what they represent.

In the two redrawn graphs (5.2), the curves are labeled directly and distinguished either by type of data-point symbol or by type of line.

Open and filled circles, as in the left graph, are the data-point symbols easiest to distinguish. They can also be used symbolically; for instance, if an experiment has been performed with (•) and without (○) treatment, the emptiness of the open circle suggests that nothing has been administered.

Other standard symbols for data points are open and filled squares and triangles (□▵▪▴). If you need more symbols, you probably have too many curves for one graph, and you should consider dividing it into two or presenting your observations in a table.

Winston Churchill was sitting at his desk, working on his epic about World War II, when his private secretary entered the room. Churchill had reached the Blitz – the German air strikes against London. His staff of researchers had earlier produced a 150-page brief on the raids. The secretary had been asked to cut it down to about two and a half pages and, after having “worked like stink,” he could now proudly hand over the condensed version.

Churchill took out his red pen and started to edit. “All my sloppy sentences were tightened up and all my useless adjectives obliterated,” the secretary tells us in a documentary made about 50 years later (Bennet 1992). In the midst of it all, Churchill said gently, “I hope you don't mind me doing this?” The secretary answered, “Thank you, Sir – you are giving me a free lesson in writing plain English.”

Brevity

We should emulate Churchill by excluding every nonessential word. Professional writers do it that way. Brevity is an elementary rule of all writing, not only to save valuable publication space, but also because verbose writing obscures meaning and wastes the reader's time and patience. And that is also the essence of the next basic rule.

Logic and clarity

To convey information is above all a matter of logic and clarity. What you want to say should be so arranged that the reader can follow your argumentation step by step.

Too often, statistics are used “as a drunken man uses a lamp post, more for support than illumination” (Sumner 1992). Experts in the field can tell whether your study really needs statistics; if it does, they can help you to plan the statistical part of your study, for example, to estimate the sample size needed to demonstrate a difference (if it exists) and to choose appropriate statistical methods.

Then, when your study is completed, you will encounter another serious matter: how to present the statistical results. About half of such presentations contain statistical errors (Murray 1991). Here are the most common ones.

Using mean when median is meant

In a descriptive study on back pain in pregnancy, the women were asked to bend over with their arms hanging down. The distance between fingertips and floor was then measured. The result (mean and standard deviation) was reported a

12 ± 14 cm,

thus ranging between –2 and 26 cm, suggesting that some of the women must have poked their fingertips a couple of centimeters through the floorboards. This surprising conclusion is the result of reporting asymmetrically distributed (skewed) data by using mean (the average) and standard deviation instead of median (the value midway between the lowest and the highest value) and a percentile range, such as the interquartile range (25th to 75th percentile).

One rule of thumb says that if the standard deviation is greater than half the mean, the data are unlikely to be normally distributed (bell-shaped).

Who should be an author? Let us discuss this delicate issue.

Guidelines on authorship

The criteria for authorship as defined by the International Committee of Medical Journal Editors (1985; 2002) are scarcely known to many scientists. And even if known, they are often ignored, as they are considered too restrictive. According to the current criteria, as of January 27, 2002 (www.icmje.org), all persons designated as authors of a paper should have

1. (1) conceived and planned the work that led to the paper or interpreted the evidence it presents, or both;

2. (2) written the paper, or reviewed successive versions and taken part in the revision process; and

3. (3) approved the final version.

As all three conditions must be met, this implies that a skilled laboratory technician who does the necessary spadework or a clinician contributing patient material is unworthy of acknowledgment as a coauthor. So, then, which guidelines for authorship are applied in the real world?

In the real world of research, most investigations nowadays are necessarily made by a team. Each member contributes different talents and skills. Irrespective of the nature of their contributions – intellectual (creative) or practical (doing the experiments) – all members of the team are usually acknowledged in the author byline.

The names also require some sort of ranking. The most prominent position, heading the list or in last place, is usually occupied by the team leader (often the author).

Michael Crichton, the author of Jurassic Park and many other bestsellers, has a background in medicine. He once wrote the following introduction for a paper published in the New England Journal of Medicine (1975):

Chrichton's first sentence awakens interest. It is succinctly written in only seven words. The entire section is short – a mere three lines long, and not a word needs to be added.

Here is another fine introduction, to a paper published in the BMJ (McGarry 1994):

This introduction, like many other well-written introductions, includes a brief description of three items:

1. (1) the problem studied or the hypothesis to be tested;

2. (2) specific findings by others that you are challenging or have developed in the study you are now presenting;

3. (3) the main features of the methods you have used.

The first point of the list should be followed by a reference to a carefully selected and recently published review article.

At one time, there were over 250 different styles of reference in the scientific literature (Garfield 1986). The editors of some major biomedical journals therefore had good reason to convene in Vancouver, Canada, in January 1978, to work out a uniform reference style. One of their suggestions was that authors should number references in the order in which they appear in the text (International Committee of Medical Journal Editors 1997).

Vancouver versus Harvard style?

Although many of the major journals in the biomedical field have adopted the Vancouver style, some still prefer the Harvard system (first used in 1881 by a zoologist at Harvard University [Chernin 1988]) in which the author's name and the year of publication are cited in the text. In the fictive sentence below, I have mixed the two styles to illustrate their differences:

Most readers prefer the Harvard system because they like to know just what author is being cited as they read the text. Still, the name-and-year system does have disadvantages: difficulty for readers who see an interesting item in the reference list in locating that reference in the main text; and, more important, the disruption of the text when a large number of references need to be cited within a paragraph, as in this example (Bengtsson 1968):

Here is a question from a course participant:

No, you aren't – if you do it politely. Thus not exactly in the way quoted below from a covering letter to the editor of Cardiovascular Research (Hearse and the Editorial Team 1992):

In this case the referee happened to be a most eminent researcher in electrophysiology. Try instead to write as though the referee were God the Father Himself. But don't hesitate to make your point:

Don't forget that the referee might have sacrificed hours of unpaid effort on your manuscript.

Do referees delay?

Here is another question from a course participant:

Toward the end of World War II, General Patton advanced with his tanks through the enemy lines. From motorcycle dispatch riders he received intelligence reports from other parts of the front. When a rider began reading out the dispatch from the very beginning, Patton most often asked him to go directly to the bottom line.

In the same way, hurried readers of scientific papers thumb through the pages to find the final paragraph of the discussion. Why? Apparently, because that is where the reader can usually get a comprehensive conclusion of the results.

But there is no generally accepted form on how to arrange the various parts leading up to the conclusion. So to help you I have chosen, as a model, an especially well-designed discussion in a paper by Logan et al. (1993). Based on this I have composed a structure for the discussion section that can be used as a guide when writing this section. It has four parts: Main message, Critical assessment, Comparison with other studies, and Conclusions. Let us discuss them step by step.

(1) Main message, which answers the question posed in the introduction section and includes the main supporting evidence.

Most often, however, the opening paragraph of a discussion unnecessarily recapitulates in detail what the readers have already been told twice, once in the abstract and again in the results section, as in the following example.

A MEDLINE search showed that no fewer than 90 percent of papers listed in Index Medicus in 1999 were written in English, compared with 53 percent in 1966 (the year MEDLINE started). The saying “Publish in English or perish” must therefore be taken seriously. Regrettably, this means that many authors are obliged to write in a language other than their native tongue – with all that this can entail. Here I will share with you an episode from my own experience as a non-native writer of English.

English as a foreign language

My first paper published in English was initially written in Swedish and then translated into English by a professional translator. “Brilliant,” I thought when I saw the translated version. But when my supervisor read it, he shook his head and said, “Try to write directly in English!” “Gosh,” I said to myself, thinking of my poor grades in English at school, “I'll never, ever be able to do that.”

But I decided to try and consulted the textbooks, which advised me to read writers of fine English, such as Gibbon and his Decline and Fall of the Roman Empire. I bought the book (running to 3616 pages in three volumes!) but could find neither the time nor the interest to read it.

Instead, I subscribed to the American weekly magazines Newsweek and Time. As they often cover the same topics, the reader is given the opportunity to learn twice, in different words, about the same issues.

It is time to write the covering letter. In most cases a letter like the following one (Figure 20.1) will suffice. Note that the second paragraph gives the essence of the paper. But you must also inform the editor in your letter if you have:

1. (1) cited unpublished observations, personal communications, or a paper “in press”;

2. (2) been involved in a financial conflict of interest; or

3. (3) divided the reporting into two papers on two aspects of the same study.

The other letter (Figure 20.2) covers all these situations. You are welcome to use those paragraphs which are relevant to your case. The new paragraphs are marked in the margin; the rest of the letter is identical with the content of the previous one.

Dear Novice Writer,

When I was in your shoes and preparing my first paper, I consulted a book on how to write. I found there a sentence encouraging the reader to stand in boiling water for an hour before doing the analysis:

I had a pretty good idea of what was wrong with the sentence but, at the time, I couldn't figure out how to revise it, and the author didn't tell me. Now I can. If, an hour later, you are still alive:

So, in this book, every unfortunate example is followed by an improved version. Good examples are provided with appropriate bibliographic references. Bad ones, however, are presented with references expunged.

Some examples were taken from manuscripts in preparation, presented by participants in my courses on scientific writing. I have been holding such courses for doctoral candidates since 1980. Other specimens are from manuscripts submitted for publication. They were collected when I served as an editor of Acta Obstetricia et Gynecologica Scandinavica from 1986 to 1994. Yet others are from published material.

From course discussions I have learned what candidates want to know. Based on this information, some chapters are more comprehensive than others, such as the one on how to prepare graphs.

Methods are usually best described in the order in which they were used. So, in the following sentence, taken from a manuscript in preparation, it would be helpful if you reversed the order of presentation, as from:

to:

Unless a previously published method is generally known, the reader will appreciate being told its essential features. Thus, a reference figure may well be considered inadequate, as in this example from a manuscript in preparation:

Little need be added to give the reader the broad outline of the method (revised text in boldfaced italics):

A new procedure, however, should be described in sufficient detail to allow a trained scientist to repeat the investigation. For the novice writer it can be hard to find a middle course between too much and too little information; often the novice errs on the side of too much. An experienced colleague can help to remove excess detail.

The subjects

I once saw a note taped to a door asking for volunteers – completely healthy, nonsmoking women aged 55 to 60 – to participate in a study of the effect of estrogen on blood circulation in the legs.

A commonly accepted practise has been to spell out small numbers, for example those below 10. However, authorities on style, such as the Council of Biology Editors' Style Manual Committee (1994, 195) and the authors of the American Medical Association Manual of Style (1998, 511), have drawn up a new rule stating that numbers should be expressed in figures rather than in words in most circumstances:

However, we should still spell out numbers that begin a sentence. The following example is from the abstract of a published paper:

But many readers find it difficult to grasp large numbers written in words, as in the example shown. Note how much easier to comprehend the passage becomes when it is recast so that the numbers fall somewhere in the middle:

Two numbers side by side

Placing unrelated numbers next to each other confuses the reader, as in this example taken from Mosteller (1992):

Separate the numbers: