Reporting Statistics and Use of Symbols in Manuscripts

Author Guidelines — Statistical Notation and Symbols

The Editorial Board requires statistical notation and symbols to be presented consistently throughout the manuscript. Authors should follow the guidelines below carefully to ensure clarity, accuracy, and uniformity in the presentation of statistical information.

1. Mean

Use the abbreviation M for the mean
Use an uppercase M without a period. When reporting a statistical value, do not spell out “mean” in place of the statistical symbol.
Avoid: mean = 4.52  /  Mean = 4.52  /  M. = 4.52
Use: M = 4.52

2. Standard Deviation

Use SD; do not use the ± symbol to represent standard deviation
Write SD in uppercase letters without periods. Do not use the plus-minus symbol (±) to indicate standard deviation.
Avoid: 4.52 ± 1.03  /  S.D.  /  s.d.  /  sd
Use: M = 4.52 (SD = 1.03)
Reporting multiple groups: Separate the results for individual groups with a semicolon.
Group A (M = 4.52, SD = 1.03); Group B (M = 3.87, SD = 0.94)
Use of the equals sign with SD in parentheses depends on context
The Editorial Board recommends the following formats according to the context in which the statistic is presented.
Statistical expression — use = for both values: M = 38.00 (SD = 3.40)
Embedded in narrative text — the = may be omitted within parentheses: The mean age in Group A was 38 (SD 3.4) years.
When SD immediately follows a numerical value in parentheses within narrative text, the parentheses already provide sufficient context; therefore, an equals sign is not essential. The most important requirement is to use the chosen format consistently throughout the manuscript.

3. Probability Value

Use a lowercase p; do not italicize it or write “p value” or “p-value” when reporting the statistic
Write p in lowercase, nonitalic type. Do not use an uppercase P, do not add the word “value,” and do not use a hyphen. Report the exact p value whenever possible.
Avoid: p value = 0.03  /  P < 0.05  /  p-value  /  p value
Use: p = 0.03    p < 0.001    p = 0.048
Very small p values: Report p < 0.001 rather than p = 0.000, because a reported value of 0.000 does not accurately represent the statistical probability.

4. Spacing Around Statistical Symbols

Insert one space before and after = < >
This rule applies to mathematical and statistical symbols for which spacing is required, whether they appear in narrative text or within parentheses. En dashes (–), hyphens (-), and minus signs (−) follow the specific spacing rules described in Section 6.
Avoid: M=4.52  /  p<0.05  /  n=80  /  SD=1.03
Use: M = 4.52  /  p < 0.05  /  n = 80  /  SD = 1.03

5. Other Common Statistical Symbols

Chi-square
Use the symbol χ² when reporting the chi-square statistic rather than spelling out “chi-square” or using other forms.
Avoid: Chi-square = 8.42  /  X2 = 8.42  /  χ2 = 8.42
Use: χ² = 8.42
Eta squared
Use the symbol η² for eta squared.
Avoid: eta squared = 0.12  /  eta2 = 0.12  /  η2 = 0.12
Use: η² = 0.12

6. Use of En Dash (–), Hyphen (-), and Minus Sign (−)

6.1 En Dash (–): Use to indicate a range
Use an en dash (–) to indicate a range or the meaning of “to” between values of the same type, such as age ranges, periods of time, years, page numbers, scores, or statistical ranges.
Important — do not insert spaces before or after an en dash: The en dash should be placed directly between the two values, for example 18–65 years, 2024–2026, and 95% CI, 1.25–2.84.
Avoid: 18 - 65 years  /  18 – 65 years  /  18-65 years  /  2024 – 2026  /  95% CI, 1.25 – 2.84
Use: 18–65 years  /  2024–2026  /  pages 125–132  /  95% CI, 1.25–2.84
Additional examples: age 18–65 years  /  follow-up period 6–12 months  /  score 0–10  /  temperature 36.5–37.5 °C
6.2 Hyphen (-): Use to connect words; do not use it to indicate a numerical range
Use a hyphen (-) to join words in compound expressions, particularly compound modifiers used before a noun, or when a standard term conventionally requires a hyphen.
Important — do not insert spaces before or after a hyphen: Words connected by a hyphen should remain together, for example cross-sectional study, case-control study, and 12-month follow-up.
Avoid: cross - sectional study  /  case - control study  /  12 - month follow-up
Use: cross-sectional study  /  case-control study  /  double-blind study  /  evidence-based practice  /  12-month follow-up
Note: Some terms are conventionally written as a single word without a hyphen, such as baseline, healthcare, postoperative, and preoperative. Authors should follow standard spelling and use the selected form consistently throughout the manuscript.
6.3 Minus Sign (−): Use for negative values
Use the mathematical minus sign (−) for negative numerical or statistical values. Do not substitute a hyphen (-) for the minus sign.
Important — the minus sign must be placed directly before the number: Do not insert a space between the minus sign and the numerical value, for example −0.42, −2.6, and β = −0.31. Spaces should still be inserted before and after the equals sign according to the journal style.
Avoid: r = -0.42  /  r = − 0.42  /  β = -0.31  /  mean difference = − 2.6
Use: r = −0.42  /  β = −0.31  /  mean difference = −2.6
Ranges containing negative values: When an en dash used together with minus signs may be difficult to read, the word to is recommended instead of an en dash, for example 95% CI, −4.1 to −1.2. This clearly distinguishes the minus signs from the symbol used to indicate the range.
6.4 Summary of the three symbols
En dash (–): Used to indicate a range, with no spaces before or after the symbol, for example 18–65 years or 95% CI, 1.25–2.84.
Hyphen (-): Used to connect words, with no spaces before or after the symbol, for example cross-sectional study or 12-month follow-up.
Minus sign (−): Used to indicate a negative value and placed directly before the number, for example r = −0.42 or β = −0.31.
Key point: Do not insert spaces before or after an en dash (–) or hyphen (-), and place a minus sign (−) directly before the number. Correct examples include 18–65 years, cross-sectional study, and β = −0.31.
6.5 How to Check and Type the Three Symbols in Microsoft Word
Because the en dash (–) and minus sign (−) may appear very similar in some fonts, authors should not rely on visual appearance alone. The correct symbol should be selected according to its function and meaning.
Key point: The dash key on a standard keyboard (-) produces a hyphen. It is not an en dash (–) and it is not a minus sign (−). These symbols should therefore not be used interchangeably.
Select the symbol according to its function
En dash (–): Use to indicate a range, e.g., 18–65 years, 2024–2026, and 95% CI, 1.25–2.84.
Hyphen (-): Use to connect words, e.g., cross-sectional study, case-control study, and 12-month follow-up.
Minus sign (−): Use to indicate a negative value, e.g., r = −0.42, β = −0.31, and mean difference = −2.6.
How to type the symbols in Microsoft Word
En dash (–):
Type 2013, then press Alt + X.
Microsoft Word will convert 2013 to –.
Hyphen (-):
Use the - key on the keyboard directly.
Minus sign (−):
Type 2212, then press Alt + X.
Microsoft Word will convert 2212 to −.
Alternative method: In Microsoft Word, select Insert → Symbol → More Symbols and choose the required symbol. Authors may also copy the correct symbol directly from these journal guidelines.
How to check the symbol when uncertain
Recommended: Determine the correct symbol from its function and context rather than from its visual length alone, because an en dash (–) and a minus sign (−) may look very similar in some fonts.
If it means “to” or indicates a range: use an en dash (–).
If it connects words: use a hyphen (-).
If it indicates a negative value: use a minus sign (−).
Avoid: Typing the standard keyboard hyphen - and using it as a substitute for both the en dash and minus sign. The three symbols have different meanings and functions.

Summary of Journal Style

Mean: M
Standard deviation: SD
Probability value: p (lowercase, nonitalic)
Chi-square: χ²
Eta squared: η²
± symbol: Do not use to represent SD
Periods in abbreviations: Do not use
Spacing around = < >: Insert one space before and after the symbol
Very small p values: p < 0.001
Multiple groups: Separate groups with a semicolon (;)
En dash (–): Use for ranges without spaces before or after, e.g., 18–65 years or 95% CI, 1.25–2.84
Hyphen (-): Use to connect words without spaces before or after, e.g., cross-sectional study or 12-month follow-up
Minus sign (−): Use for negative values and place it directly before the number, e.g., r = −0.42
Note for Authors: If a manuscript does not conform to the prescribed format, the Editorial Board reserves the right to return the manuscript to the authors for correction before it proceeds to peer review. Authors are responsible for maintaining consistent statistical notation and formatting throughout the manuscript.