4. Numbers, Dates, and Measurement

Words vs Numerals

Write out one through ten unless immediately followed by a unit or symbol.
Examples: three participants; 5%; 10° Celsius; 3 pm.

Percentages

Always use the % sign with an Arabic numeral.

Time Notation

Use lowercase h, m, and s in 24-hour notation.
Examples: 13h00; 13h21m48s.
Avoid colon-separated time (13:21:48) and avoid am/pm or “o’clock”.

Dates

Numeric dates use leading zeros and hyphens: 02-12-2025.
Order: day–month–year.
Long-form example: Tuesday, 2nd December 2025.

Thousands and Decimals

Thousands separator: comma
Decimal separator: full stop

Ranges

Use en dashes and place the unit after the range: 5–10 km.

APA Numerical Conventions

Values bounded by ±1 omit the leading zero (r = .389).
Round to three decimals unless APA requires otherwise, e.g. SD and M.
Use M when following APA; use x̄ when APA formatting does not apply.

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