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Clinical Chemistry 56:10
1528–1534 (2010)
Clinical Chemistry
Guide to Scientific Writing
Bring Your Best to the Table
Sometime in the past you were likely taught about the text (e.g., mass transitions for 20 different drugs being importance of “bringing your best to the table”—in other words contributing your best ideas and results.
A good table, although used for a purpose different Indeed, it is an important key to success. But what ideas from that of a good graph, has many of the same at- and results you bring to the table may not be enough.
tributes (4 ). A table should draw attention to the data Sometimes it is how you present your ideas and results and not to the table itself. In other words, the data that distinguishes you and determines your success.
within the table should be easy to distinguish and not This consideration also holds true while writing a be lost among poorly arranged words and numbers.
scientific paper, when you want to bring your best to Every table should have a clear and concise title. The another type of table—the table within your manu- table should stand alone without the need to refer re- script that shows your data. With this type of table, it is peatedly back to the main text. Lastly, the data must also important to understand that how you present deserve to be in a table rather than in the main text.
your data can affect the success of your paper. In thisarticle, I provide some basic tips on how to create a Table Components
table that presents your data in a clear and visually ap-pealing manner.
Scientific tables contain 5 major elements (Fig. 1): atitle, column headings, stubs (row headings), data Tables vs Graphs
fields (the spaces in the columns that contain the data),and footnotes (2 ). Sometimes a table may contain a Data can be presented in either a graph or a table, so spanner, a heading separated by a horizontal line that how do you choose which is best when writing a scien- sits above secondary column headers. A spanner indi- tific paper? Let’s compare the two. Graphs have an im- cates that the column headings below it should be con- mediate visual impact and are good for showing trends sidered as part of a common group. Copy editors and or patterns or for highlighting differences between sets printers will sometimes query an author about one of of data. Although the data in a graph are quantitative, a these table elements, so it is important to understand graph does not work well when the exactness or preci- how each of these elements fits into the presentation of Tables, on the other hand, are better when the in- The title of a table should be sufficiently informa- dividual or summarized values are more important tive for the reader to understand the experimental data than trends. Tables can be used for presenting both being presented without having to refer to the paper.
quantitative and qualitative data (1 ). A table can con- Consider the following 3 hypothetical titles: tain words, symbols, numbers, or a combination of allthree (2 ). Tables allow side-by-side comparison of data Example 1: Statin therapy and cancer recurrence. (3 ), such as the imprecision of 2 assays at several ana- Example 2: Effect of daily oral primvastatin or dor- lyte concentrations. Although there is often a direct vastatin on the 4-year odds ratio for the recurrence of relationship between the variables listed in a table (e.g., death or myocardial infarction vs the tertile for a cys- Example 3: The effect of daily oral primvastatin or tatin C concentration), the variables in a table do not dorvastatin on the 4-year odds ratio (OR) for the recur- need to have a direct relationship. Tables are also good rence of prostate and breast cancer shows a 3-fold lower for presenting large amounts of information that (P ϭ 0.002) OR for the recurrence of breast cancer for would be too cumbersome or confusing to place in the patients receiving primvastatin (OR ϭ 2.3) versus dor-vastatin (OR ϭ 6.8). Unless the headers or footnotes in the table in- clude the names of the statin drugs tested, the type ofcancer, the time period of the study, and the end point University of Michigan Health System, Ann Arbor, MI.
* Address correspondence to the author at: University of Michigan Health System, being measured, the title in example 1 may force the Rm. 2G332, 1500 East Medical Center Dr., Ann Arbor, MI 48109-5054. Fax reader to look back at the experimental methods sec- 734-763-4095; e-mail [email protected].
tion of the paper to understand the context of the data Received July 14, 2010; accepted July 22, 2010.
Previously published online at DOI: 10.1373/clinchem.2010.153502 being presented in the table. Example 2 is an informa- Clinical Chemistry
Guide to Scientific Writing
Serum antiproxin and interleukin-6 concentrations in patients with congestive heart failure.
Antiproxin Interleukin-6
_____________________ ______________________ Concentration, Concentration,
Stage classification
P
P
b P values compared with healthy individuals.
Fig. 1. Major components of a scientific table.
tive title that tells the reader much more about thestudy design (a 4-year follow-up study), the measuredend point (odds ratio for recurrence), the specific dis- Table 1. Options for displaying annual per capita
eases being studied (prostate and breast cancer), and healthcare expenditures.
the therapeutic agents being tested. The title in example3 contains the same useful information as in example 2 A. Annual per capita healthcare expenditures.
but makes the mistake of providing the data and results Expenditure, $
as well. Titles should not include experimental details, data, or results. The data belong in the data fields of the table. Results and experimental details belong in the The far left column containing the stubs lists one or more variables, usually the independent variable(s). All ofthe remaining columns to the right of the stubs must link B. Annual per capita healthcare expenditures.
back to the rows. This first column may not require a Expenditure, $
column header if the meaning of the stubs is evident (Ta- ble 1). If the variables have units (e.g., time, concentra- tion, percent), these units should be added in parentheses or after a comma. If the variables all have the same units, the common unit can be designated after the main header When listing units of measure, be sure to use the C. Annual per capita healthcare expenditures.
journal’s required format. Many journals, including Expenditure, $
Clinical Chemistry, request that SI units be used throughout a scientific paper. In the text, conventional units may be added in parentheses after SI units, but a different format should be used in a table. In a table, one should use the primary units in the body of the table and provide conversion factors to the secondary Clinical Chemistry 56:10 (2010)
Clinical Chemistry
Guide to Scientific Writing
Table 2. Long-term outcomes according to cystatin C tertile.a,b
Cystatin C tertile
First tertile: <0.86
Second tertile: 0.86–1.01
Third tertile: >1.01
mg/L (n ؍ 378)
mg/L (n ؍ 365)
mg/L (n ؍ 385)
Log-rank P
a Data are presented as percentages from Kaplan–Meier curves at long-term follow-up; the number of events is in parentheses.
b Table from Clin Chem 2009;55:1118 –25. Used with permission.
(i.e., conventional) units in footnotes, which are dis- follow some general rules for formatting and The remaining columns, which usually represent the dependent variables, should each have a concise heading.
• The stubs should all be left justified.
Because the units in each data field of a column are typi- • In the columns/data fields, words should be left jus- cally the same, it is acceptable to state the units just once in tified, and whole numbers should be right justified.
the column header, either in parentheses or after a • Data fields containing decimal points, plus/minus comma, rather than to repeat the units after each value. If symbols, slashes, hyphens, or parentheses should be you have missing data or no applicable entry for a data field, do not leave the space blank, because the reason for • When the text in a stub wraps to a second line, the corresponding data field should align with the top the missing entry may not be clear to the reader. If there are no data for that field, you can insert an em dash (—) oran ellipsis (. . .) to designate that no data are available. The Some examples show how these alignment rules abbreviation NA can also be used, but it must be defined help improve the clarity of a table. Table 1 shows the in a footnote, because NA can be interpreted as “not ap- annual per capita healthcare expenditures for a set of plicable,” “not available,” or “not analyzed” (2 ).
countries. Note how the names of the countries in the Each footnote should be placed on a separate line stubs and the numbers in the column are easier to read at the bottom of the table. Most journals recommend when they are justified appropriately (Table 1A), com- that superscripted letters rather than numbers be used pared with the centered spacing often seen in drafts of to designate footnotes, because a superscripted num- papers (Table 1B). Because the meaning of the stubs is ber can be confused with an exponent. Some journals evident, it is not necessary to add a heading for the prefer the use of symbols to numbers for designating stubs. Also note that the unit of measure ($) for the data footnotes, so it is wise to read the selected journal’s is placed after the column heading because the same submission requirements. Letters (or numbers, or unit applies to all of the data fields.
symbols) designating footnotes should be ordered al- Long-term outcomes according to cystatin C ter- phabetically (or numerically), starting with the title of tile are shown in Table 2. Because the meanings of the the table and then working left to right and down, just stubs are evident, no heading is necessary. Entries in as in reading text. The symbol designating a footnote the stub column are left justified. The numbers (per- that applies to the entire table should be placed after the centages) in the data fields contain a decimal point; title. Symbols for footnotes that apply to an entire row therefore, the numbers in each column, including the or column should be placed after the row or column P values in the last column, are aligned with the decimal heading (Fig. 1), and those that apply to a single data point. Note that to fit within the width of the stub col- field should be added after the entry for that field (2 ).
umn, the text in the fourth row has wrapped to a newline, but the corresponding data fields in this row have Table Alignment
remained aligned with the top line of the stub.
Table 3 also illustrates many of the concepts de- As an author, you can help your tables make a positive scribed earlier for creating an effective table. The title is visual impression and make them easy to read if you sufficiently informative that a reader can understand Clinical Chemistry 56:10 (2010)
Clinical Chemistry
Guide to Scientific Writing
Table 3. Phenytoin concentrations measured by
Table 4. Two ways to list the top 10 states for
immunoassay for matrices supplemented with
air quality.
10 mg/L phenytoin.
A. States with the 10 highest air quality indices.
Deviation
Mean (SD),
Mean ؎ SD,
target, %
B. States with the 10 highest air quality indices.
the experiment performed and the data produced. The stubs are left justified, and their meanings are suffi- ciently clear from the title that a header is not needed.
The units are placed in the headers for the columns because the units apply to all of the data in the column.
Two different styles for presenting the mean and SD are shown in columns 2 and 3. In column 2, which follows Clinical Chemistry style, the data are aligned on the dec- imal point. Some journals allow the style shown in col- umn 3, in which the data are aligned on the common element (Ϯ). In the last column, the numbers are right justified regardless of whether the numbers are positiveor negative. It might help to pretend that a decimalplace exists after each whole number and that you are country names are listed alphabetically, and the reader aligning the numbers with this decimal point.
is not drawn to any pattern in the data. Rather, thereader must look for the country of interest and then Tables of Lists and 2-Column Tables
find the corresponding dollar expenditure for thatcountry. This ordering helps the reader find specific Sometimes a table can be a simple list of information, information. The layout in Table 1C helps the reader such as the exclusion criteria for a clinical trial, instru- see a pattern. The dollar values in the data field are ment settings, or sequences of primers used in a PCR ranked from highest to lowest, and the reader is drawn assay. Although the items in such lists may not have any to the pattern of the data rather than to the country inherent rank or order, how you decide to order them names. Again, how you organize the table can affect may affect what the reader infers (3 ). Table 4 illustrates 2 ways to list the top 10 states for air quality. Table 4Astarts with Idaho and ends with Tennessee. As a reader, The Best Tip of All: Keep Your Tables Small
I would infer that the point of the table is to show thatIdaho is the top state for air quality and that Tennessee One trap that authors often fall into is to assume that all is 10th among the 50 states, but if the states were ranked acquired data should be placed in a table. In an attempt alphabetically (Table 4B), I would infer that the point is to be comprehensive in providing information, you simply to list the top 10 states, with no implication may create a table that is so large and complex that the regarding which state was best in air quality.
important data—and the message— get lost among With a 2-column table (Table 1), you have the column after column (or row after row) of informa- choice of ordering either the stubs or the data fields.
tion. The data that belong in a table are the data that are Lang refers to this choice as helping the reader see spe- essential for conveying the results you want the reader cific information (organizing the table from the out- side in) vs helping the reader see patterns (organizing So what is the right size for a table? A useful rule the table from the inside out) (5 ). In Table 1A, the provided by Huth (6 ) is that the maximal width should Clinical Chemistry 56:10 (2010)
Clinical Chemistry
Guide to Scientific Writing
be 60 characters and spaces in a row for a table runningacross half a page and 120 characters and spaces for atable running the full width of a page. For a 2-column journal such as Clinical Chemistry, a table width of 110 characters and spaces would fit onto a portrait- formatted page. Otherwise, a journal might consider leukemia,
publishing the table in landscape format (sideways), Megakaryoblastic
but this formatting is awkward for the reader and justdoes not look as nice on the page (Tables 5 and 6).
Fortunately, there are several ways to condense the size of a table. One is to reorient the table so that the variables are reversed in the table (6, 7 ), as shown inTable 7. This table contains the same data as Table 5 but leukemia,
uses half the width. It also fits a portrait layout on the Microkaryoblastic
journal page. If the ratio of the number of columnheadings to row headings is greater than 2:1, you should evaluate whether reorienting the table would leukemia.
allow a better presentation of the data (6 ).
Another option is to evaluate whether all of the columns or rows are necessary in a table and whetherany nonessential data can be removed. In Table 6, for Erythroleukemia,
example, are all of the data and text in the first 3 col- myelogenous
umns necessary? Will the first author and reference number suffice to identify the studies? Is there a strong reason (e.g., the differences in the number of patients are critical to your discussion) to include the number Monocytic
leukemia,
and sex of the patients if the same information can be found in the reference? Isn’t the initial value for a vari- able, such as the leukocyte count, typically considered 100%? Condensing column 1 and removing columns 2and 3 yield a table (Table 8) that is narrower and looks survival
cleaner on the printed page. Other columns of data that leukemia,
could be removed and explained in a footnote include Myelomonocytic
those that contain a single data point, a column in which all of the values are the same, or a column in which only 1 or 2 of multiple values differ from theothers (e.g., 9 positives and only 1 negative). If a col- umn contains a series of P values with only 1 or 2 being Age-related
Promyelocytic
leukemia,
statistically significant, this column could be replaced with superscripted letters or symbols after the values,with the significant differences and explanations pre- The use of abbreviations instead of longer names also can reduce the width of a table substantially. Jour- Myeloblastic
leukemia,
nals allow more leeway in the use of abbreviations intables because the definitions can be provided in foot-notes. As an example of this approach, one could try to abbreviate the types of acute myelogenous leukemia in Table 5 (e.g., UL, undifferentiated leukemia; MML,myelomonocytic leukemia; EL, erythroleukemia). Try leukemia,
Undifferentiated
this, and see how much this table could be condensedby doing so.
If you have data that could be removed from a large table but are of consequence for the reader to bestunderstand your message, consider placing the most Clinical Chemistry 56:10 (2010)
Clinical Chemistry
Guide to Scientific Writing
Table 6. Previous studies of leukocyte reduction during kelvac therapy in patients with chronic
myelogenous leukemia.
Leukocyte count, %a
patients
a Percentage of initial value at start of treatment.
b Ref, reference; M, male; F, female.
important data showing the results in a printed table effort creates a good impression. My advice is to make and placing the secondary data in a supplemental or the effort up front to split the table.
online table. In the current era of electronic publishing,most journals make use of these supplemental elec- Learning Exercise
tronic files as a way to optimize the use of an article’sallotted page space, yet such files still allow authors to Look at Table 9. This table can be improved in several provide secondary details and data in an easily accessed ways to make it more clear and informative. Compare your suggested changes with those provided at the end Sometimes the best option is to split a large table into 2 separate tables. Authors tend to avoid this in anattempt to count 1 large, complex table as a single table Final Thoughts
to stay within the journal’s limit on tables and figures.
This trick more often backfires than helps, however. It When you write a paper, you know that any typograph- takes a peer reviewer more time to try to understand a ical and grammatical errors will be corrected during the large table, it takes more time and money for an editoror copy editor to reformat the table, and it takes moretime for the reader to understand. None of this added Table 8. Previous studies of leukocyte reduction
during kelvac therapy in patients with chronic
myelogenous leukemia.
Table 7. Age-related 5-year survival for forms of
acute myelogenous leukemia (AML).
Leukocyte count, %a
(reference)
a Percentage of initial value at start of treatment.
Clinical Chemistry 56:10 (2010)
Clinical Chemistry
Guide to Scientific Writing
Table 9. Effect of tacrolimus or sirolimus on everolimus measurement.
Specimen
Measured concentration
Pa
a P value compared with everolimus alone. P Ͻ 0.05 considered significant.
final editing process. Nonetheless, you always perform a Consultant or Advisory Role: None declared.
spelling and grammar check, because you know that con- Stock Ownership: None declared.
fusing or poorly composed sentences do not make a good Honoraria: None declared.
Research Funding: None declared.
impression during the review process. The same holds Expert Testimony: None declared.
true for tables. Although the editors and printer will makesure that your table is formatted properly before publica- Role of Sponsor: The funding organizations played no role in the
tion, the time to make the best impression is during the design of study, choice of enrolled patients, review and interpretationof data, or preparation or approval of manuscript.
review process. A table that not only is easy to read but alsoemphasizes the point you are trying to make will get youstarted on a solid footing.
References
1. Hamilton CW. On the table. Chest 2009;135:1087–9.
2. Iverson C, Christiansen S, Flanagin A, Fontanarosa PB, Glass RM, Gregoline B,
Author Contributions: All authors confirmed they have contributed to
et al. AMA manual of style: a guide for authors and editors. 10th ed. New the intellectual content of this paper and have met the following 3 re- York: Oxford University Press; 2007.
quirements: (a) significant contributions to the conception and design, 3. Browner WS. Publishing and presenting clinical research. Philadelphia: Lip-
acquisition of data, or analysis and interpretation of data; (b) drafting pincott Williams & Wilkins; 2006.
or revising the article for intellectual content; and (c) final approval of 4. Annesley TM. Put your best figure forward: line graphs and scattergrams. Clin
Authors’ Disclosures of Potential Conflicts of Interest: Upon
5. Lang TA. How to write, publish, and present in the health sciences.
manuscript submission, all authors completed the Disclosures of Poten- tial Conflict of Interest form. Potential conflicts of interest: 6. Huth EJ. Writing and publishing in medicine. 3rd ed. Baltimore: Lippincott
Employment or Leadership: T.M. Annesley, Clinical Chemistry,
7. Zeiger M. Essentials of writing biomedical research papers. New York:
1. The title would be more informative if it included the analytical technique or assay used.
2. An em dash may be added to the last column.
3. Because the unit of measure is the same for each concentration measured, it could be presented once after the corresponding column heading.
4. The numbers, including the P values, should be aligned on the decimal point.
5. The information in the stubs for the second and third rows wraps to a second line. The data in the column entries should be aligned with the top line of the corresponding stub.
6. Because only 1 P value is statistically significant, one could remove the last column and provide the Clinical Chemistry 56:10 (2010)

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