Guidelines for Statistical Reporting
Prior to publication, manuscripts are edited to adhere to Journal style. Statistical reporting formatted to Journal style shortens the production process and reduces the number of changes made to a manuscript following acceptance. The following is a comprehensive guide to formatting statistics to Journal style.
For any statistical formatting questions/concerns not covered by this guide, please contact production@jrheum.com.
If the digit on the right of the last significant digit is 5 followed by any number (except 0), the last significant digit is rounded up.
Mathematical Symbols
The equality signs, “greater than or equal” and “less than or equal,” should be represented by the symbols ≥ and ≤, respectively. Note that these are not underlined “greater than” or “less than” symbols.
Insert spaces on either side of mathematical symbols.
To represent minus, use the minus symbol (–) and not a hyphen (-).
Example:
5 – 4, NOT 5 - 4.
To represent multiplication, use the multiplication symbol (×) and not the letter x.
Example:
5 × 4, NOT 5 x 4.
Population Size (N and n)
N should be used when referring to the entire population under study.
n should be used for a sample of the population under study.
Example:
N = 350, n = 163
Percentages
Percentages should be rounded according to the total sample size:
- If N < 100, percentages should be reported as whole numbers.
- If N is between 100 and 999, percentages should be reported to 1 decimal place.
- If N ≥ 1000, percentages should be reported to 2 decimal places.
If a table contains varying sample sizes, use a consistent number of decimal places. For example, if most sample size values are over 1000, use 2 decimal places for all percentages, even if there are sample size values less than 1000.
Exception:
Trailing zeros after the decimal point should always be omitted.
There should be no space between the number and the percentage sign.
It is preferable to indicate both the numerator and denominator associated with each percentage.
Examples:
n = 53/84, 63%
n = 193/330, 58.5%
n = 1536/2003, 76.68%
Mean and Standard Deviation
Mean and SD should be reported to 1 decimal place.
SD should not be expanded upon first use.
SD should be reported in brackets after mean. The ± symbol should be avoided.
Example:
Mean 49.1 (SD 0.4) years, NOT mean 49.1 ± 0.4 years
Odds Ratios and Confidence Intervals
ORs should be reported with CIs.
OR should be expanded upon first use; CI should not.
ORs and CIs should be reported to 2 decimal places, except when the significance is affected.
CIs should be reported as hyphenated ranges. However, if one of the values in a CI range is negative, “to” should be used between the values instead of a hyphen. When this occurs in a table, “to” should be used for all CI ranges in the table.
Examples:
Odds ratio (OR) 0.34 (94% CI 0.11-1.01)
13.9% (95% CI −0.71 to 30.55)
Interquartile Ranges
IQR should not be expanded upon first use.
IQRs should be reported as a hyphenated range. Reporting the 25th and 75th percentiles separated by a comma or slash symbol should be avoided.
IQRs should ideally be reported to one decimal place.
Example:
Median 24.2 (IQR 21.1-25.1)
P Values
P should be capitalized and italicized.
The lowest P value reported should not be less than P < 0.001; the highest should not be greater than P > 0.99.
P values less than 0.001 should be reported as P < 0.001.
P values should be reported to 2 decimal places, except when the significance is affected.
In a table heading, the heading should be “P” not “P value.”
Examples:
P = 0.12
P < 0.001
P > 0.99
Chi-square Test
Chi-square values should be accompanied by 3 degrees of freedom and should have no more than 1 decimal place.
Example:
Chi-square = 76.8, P < 0.001
Greek Symbols
Greek symbols should always be used, as opposed to spelling them out.
Example:
Cohen weighted κ, Spearman rank correlation (ρ)
Exception:
For chi-square test, the chi symbol should only be used in an equation.
Eponyms
The possessive form for eponymous terms should not be used.
Examples:
Spearman correlation coefficient, NOT Spearman’s correlation coefficient
Fisher exact test, NOT Fisher’s exact test
Equations
Equations should be inserted using the Advanced Symbols in Microsoft Word. The Equation Editor in Microsoft Word should not be used.
The MathType extension (https://www.wiris.com/en/mathtype/) is the preferred tool to be used for larger equations.
Other
Leading zeros should always be present for values less than 1.
Examples:
0.001
0.43
Semicolons should be used to separate multiple unrelated statistics in a sentence. Related statistics should be separated by commas.
Examples:
Comma separated: (OR 4.06, 95% CI 1.80-9.17)
Semicolon separated: 57.8% (fatigue score > 7; P < 0.001)
An equal sign is not necessary when reporting coefficients, hazard ratios, odds ratios, risk ratios, etc.
Example:
ICC 0.85 (95% CI 0.81-0.89)
Tables
For table footnotes, use lowercase letters in alphabetical order (a, b, c, etc.).
Exception:
For P values in a table that require footnotes, use asterisks (*, **, ***, etc.).
Units should not be used in table cells, only in table headers or captions.
In Table headers, units should be separated by commas and not parentheses.
Examples of Tables:
The following are examples of properly formatted tables.
Reporting percentages and mean (SD):
Reporting 95% CIs, ORs, and P values:
Reporting mean (SD), percentages, and P values, and examples of footnotes:
Reporting P values and negative 95% CIs:
Reporting ORs, 95% CIs, P values, and IQRs, and examples of footnotes:
Reporting IQRs and percentages:
