Scientific Writing Table: Part-3 Summary of last session Title: Informativness without text: group...

Scientific WritingTable:

Part-3

Summary of last session

• Title:

• Informativness without text: group Vs given name…• Topic or point• Independent variable(s) (X), • Dependent variable(s) (Y), • Animal or population, the material described, or both (Z).

• Category term• Headings• Dependent and independent variables• Use the same key terms in the title, the column headings, and

the text of the paper• Informative

Headings

• Do not omit the column heading that states the name of the dependent variable [for example, “Recovery (%)” in Table 5], even in simple tables that have only one dependent variable that is named in the title.

• It is clearest for the reader if the dependent variable is named both in the title and in the column headings.

Subheadings• In the column heading

the dependent variable and the unit of measurement are in the main heading and two sites in which this variable was measured are in the subheadings. (See also Tables 2, 4, and 5.)

• Note that terms in column headings and subheadings are singular, not plural (for example, “Recovery,” not “Recoveries”).

lf necessary, number columns or rows to help integrate the text and the table.

• A table can sometimes require extensive explanations in the text, and extensive explanations in the text sometimes require frequent reference to a table.

• In such cases, it can be helpful to number the column or row heads to help readers find their place in the table faster .

lf necessary, number columns or rows to help integrate the text and the table.

Building A table

Title Column headings

Foot notes

Row headings

Fields

• The purpose of a table determines how you construct it: Form follows function. If the table's purpose is to compare subjects at different times, for example, then you will want to format the table so that this is easy to do, by placing the times side by side in columns (Table 6.3).

Table Formats

• The rules on which words in a table title should be capitalized will vary from journal to journal.

• Follow journal guidelines :– roman or arabic numbers;– centered or flush left table number, title, column,

headings, and data; – capital letters and italics;

Building A table


Foot notes

Row headings

Fields

BUITDING A TABTE: The Field

If an intersection does not have a datum, the absence should be indicated bythree ellipsis dots (. . .) or an abbreviated notation explained in a footnote,such as ND for "Not done" or NA for "Not available', or .,Not applicable".

The Field

• To save space, editors often allow some abbreviations to be used in tables that they would not allow in text.

• All abbreviations in tables (but nor standard symbols for units of measurement) must be explained in footnotes, even if they are abbreviations explained in the text.

The Field• Placement of standard deviations can be

difficult, especially in the case of several columns.– If placed to the right of the mean, reading and

comparison of standard deviations across rows are hindered.

– Likewise, if the standard deviations are placed below the mean, reading and comparison along rows are hindered.

Tables: baseline, descriptive data

Standard deviation

n

Women’s health Initiative, JAMA, 2002

Building A table


Foot notes

Row headings

Fields

Footnotes

• The footnote 1. defines the kind of data,

2. the number of patients studied,

3. The observation points,

4. the abbreviations,

5. the statistical significance level, and

6. the statistics used.

Footnotes

• For example, "12.1 +_ 0.3" could indicate a mean of l2.l with a standard error of the mean of 0.3 or a standard deviation of 0.3 for the distribution of the values represented by the mean.

• Keep footnotes to a minimum. They should only be used to explain essential details and abbreviations.

The footnote defines the kind of data,1. the number of patients studied, 2. the observation points 3. the abbreviations 4. the statistical significance level5. the statistics used.

Footnotes

From: nurses health study

general accepted standards

• Although certain aspects of table format differ between journals, some generally accepted standards exist.

• Three horizontal lines are usually used to separate parts of the table:– one above the column headings, – one below the column headings, and – one below the data (to separate the body of the table

from the footnotes).

Tables: baseline, descriptive data

Table 1. Base-Line Characteristics of the Women Who Underwent Radical Mastectomy and Those Who Underwent Breast-Conserving Therapy.

Veronesi et al. Twenty-Year Follow-up of a Randomized Study Comparing Breast-Conserving Surgery with Radical Mastectomy for Early Breast Cancer NEJM 347:1227-1232; October 17, 2002

Three horizontal lines

Exercise : Checklist • Title

• Headings

• Field: comparison, precision…

• Footnote ( 4 parts)

Exercise BMJ step by step

Table 4.1 is an example of a poor table.• The title does not explain the

initiating stimulus to the observed responses.

• It lists individual haemodynamic variables rather than using a category term.

• The "condition" is poorly defined. • All of the vertical and most of the

horizontal grid lines are superfluous. The columns have no indication of the units used.

• The results for cardiac output show more decimal places than the precision of the measurement justifies.

Table 4.1 is an example of a poor table.

• The ± value is not defined (is it standard deviation or standard error of the mean?).

• No mention is made of the number of participants studied.

• The changes run from top to bottom rather than from left to right across the page.

• Abbreviations are not explained.

• No indication is given of any statistically significant changes.

Consider now a revised version of the same table (Table 4.2).

• The title describes the initiating stimuli ("Induction of anaesthesia and sternotomy") and uses a category term ("cardiovascular").

• The superfluous grid lines are eliminated. Changes run across the table from the left-most column.

• The subheadings ("Before", "After", "During", and "After") allow clear chronological allocation of observation points.

Consider now a revised version of the same table (Table 4.2).

• Units of measurement are provided. The asterisks in two columns are a clear signal of a statistically significant difference (the absence is a clear signal for the lack of such a difference).

• The footnote defines the kind of data, the number of patients studied, the observation points, the abbreviations, the statistical significance level, and the statistics used.

• This table can now stand on its own. Your reader will be able to obtain all the information they need without having to refer back to the text.

Next sessions

• Part 4: – How Should Be Compared? (How to

complement results with tables ?)

• Part 5: – What Should Be Compared?

how to complement results with tables ?

Part-4 Akbar soltani, MDShariati Hospital

www.soltaniebm.comwww.ebm.ir

www.avincennact.org

Scientific Writing

GETTING STARTED

• Many beginning investigators make the mistake of writing their results section around their tables and figures.

• The resulting manuscript reads like a boring tour of an art museum.

• Picture 1 is by van Gogh. That sculpture is by Matisse. The next painting was painted in 1904.

• Table 1 shows. . . . Figure 1 demonstrates. . . . The multivariate results can be seen in Table 2. . . . Figure 2 is the survival curve.

GETTING STARTED

• While there is nothing intrinsically awful about this type of paper, it violates a key rule, that the text, tables, and figures should complement one another.

• What does complement mean? • If the table gives the participants' mean weights and

cholesterol levels, and the proportions who had diabetes and hypertension, then you might say this in the text:

• Participants were generally obese with a high prevalence of cardiovascular risk factors (Table 5.1).

Complementmeans

Logical structure

What does complement mean?

TABLES OF LISTS• Some tables are just lists of items,

such as diagnostic criteria or types of bacteria that cause urinary tract infections.

• The essential decisions are what to include and in what order.

TABLES OF LISTS• A list may not have an intrinsic order, such as

the causes of hyperkalemia, or it may have an order that is essential to the point you are trying to make, such as the frequency of symptoms in a patient with Cushing's syndrome.

• Beware of imposing an order that confuses your point. It makes little sense, for example, to alphabetize urinary tract pathogens (Table 6.8).

TABLES OF LISTS

• The sequence in such tables should have a readily grasped logic: – descending order of frequency; – grouping by body systems; – chronologic order, – or some other clear basis.

• A better approach is to list the pathogens by frequency, perhaps subcategorized by type. A more informative title and headings also help (Table 6.9).

• Table 6.9 demonstrates an important rule: Avoid using percents of percents. Each percentage in a column should refer to the same denominator. If you want the reader to notice that half of the gram-positive species were Staphylococcus aureus, then say so in the text: "We cultured several different organisms (Table 6.9). Staphylococcus aureus accounted for half of the gram-positive culture results."

• Note that the percentages for the two most common types of gram-negative pathogens do not sum to the total for all gram-negative bacteria; this immediately informs the reader that other species were seen. If these species matter, they could be included in a footnote. The percentages for specific gram-negative (and gram- positive) organisms are offset slightly, to indicate that they are a part of the total for that group. The numbers of each pathogen have been omitted intentionally; they would be included only if you wanted readers to be able to check your arithmetic.

TABLES OF SUBJECT CHARACTERISTICS

• Ask yourself what readers will want to know about the subjects. How does the example (Table 6.10) look?

• At first glance, the table may look fine. But it is loaded with problems.

• The title is generic: which subjects and how many? Stating the proportions of subjects who were male, and then doing the same for female subjects, is not necessary.

• The extraneous variables and unnecessary precision are distracting; will anyone really care about the subjects' mean shoe size, or that exactly 8.63% of subjects had a history of diabetes?

• The table mixes dichotomous data, such as history of diabetes, with continuous data such as body weight.

• There is an undefined abbreviation (CHD), the columns are not labeled, the units are not provided for age and body weight and they do not make sense for caloric intake, and the meaning of the plus-minus values is not specified.

• Exercise: Consider the improved version, Table 6.11.

Complementmeans

Logical structure

Contrast(differences)

Overall result

The most Common…

Compare(similarities)


• The text that accompanies the table might simply read, "There were similar numbers of men and women in the study (Table 6.11); 33% of the subjects were over 65 years of age, and 25% were more than 10 kg above ideal body weight. Most were free of chronic medical problems."

• An acceptable alternative, especially if the exact numbers do not matter very much, is to list the percentages and means (Table 6.12).

Complementmeans

Logical structure


Stratify

Overall result

The most Common…



• Occasionally, it is worthwhile to divide (stratify) the information on the subjects into two groups (e.g., men and women). This type of table is most useful if there are important differences between the two groups; which should be pointed out in the accompanying text:

• Text: "Diabetes was 40% more common among women, whereas male subjects were more than twice as likely to have reported a history of heart disease."

Complementmeans

Logical structure


Emphasize

Overall result

The most Common…



• The text can also be used to emphasize other aspects of the sample, such as the fact that the numbers of men and women were similar, or that the overall mean age was 64 years (Table 6.13).

Complementmeans

Logical structure


Emphasize

Overall result

The most Common…


categorize outcomes


TABLES THAT,TELL WHAT HAPPENED

• If the manuscript reports the results of a randomized trial, then the characteristics of the subjects need to be presented for each of the study groups.

• Percentages-rather than numbers-of subjects may be easier to follow.

• This is especially true if the numbers of subjects in the groups vary substantially (e.g., because twice as many subjects were randomly assigned

to the treatment as to the control group).

Categorizing outcomes

• Tables are useful if there are several outcomes of interest (e.g., death, myocardial infarction, and hospitalization).

• Tables are also valuable when you wish to categorize outcomes into different classes, such as deaths due to cancer and deaths due to cardiovascular disease, and especially if you want to subcategorize them further, such as by types of cancer.

Outcome Vitamins PlaceboRRI

(95%CI)NNH

All cause mortality

14.1% 13.5%4%

(-3_12)Not significant

Vascular

Mortality 8.6% 8.2%

5%


Non vas

Mortality 5.5% 5.3%

4%


Major coronary event

10.4% 10.2%2%


Outcome Vitamins PlaceboRRR

(95%CI)NNT

Stroke 5% 5%1%

(-12_13)

Not significant

Revascularisation

10.3% 10.6%2%

(-6_10)

Not significant

Cancer 7.8% 8%

2%

(-8_11)

Not significant

Thank you

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