Eva van Emden, Freelance Editor

Certified Copy Editor and Proofreader


February 20, 2011

Making your science papers look good

The more polished your paper is when it goes to reviewers and committees, the more likely it is to be read favourably. Getting the small things right will inspire confidence that you got the big things right too, but a lack of consistency and attention to detail in layout, spelling, and punctuation will make the reader wonder what else you didn’t pay attention to. Here are some basic points that I often find myself correcting when editing papers.


Put a space between the number and the unit (5 km, 200 g). The exceptions are degrees of temperature or latitude (N 49°15′48.14″, W 123°9′43.34″, 5°C, 5°F), percent signs (5%), and prime signs (6′2″). Some styles allow a space before the degree symbol in temperatures (5 °C). (The symbols for minutes and seconds in latitude and longitude or feet and inches are the prime and double prime. See “Special characters” below.)

Capitalization: the abbreviation for litre (L) and millilitre (mL) may use a capital L to distinguish it from a 1 (one).

When two quantities go together, repeat the symbol only if there is no space between the number and symbol (CMOS 9.17): 3%–5%, 4–5 km, 6″ × 9″, and 39°C–40°C.


You’re likely to have a lot of numbers in your text. Here are a few guidelines.
  • Use en dashes instead of hyphens in ranges of numbers (8–10). The en dash is slightly longer than a hyphen.
  • When writing in English, use a period (not a comma) for the decimal point, and commas (not periods) to separate groups of three digits. Some styles use spaces to separate groups of three digits. It is also permissible to omit the comma in a four-digit number. Be consistent.
  • Numerals versus spelled-out numbers. In the absence of other instructions, a safe policy is:
    • Spell out single-digit numbers and use numerals for all others: “all three study areas,” “in 2.3% of the samples.”
    • If a number is given with a unit, use the numeral even if it’s a single-digit number: “each test tube contained 2 mL of solution” (not “two mL”).
    • If you start a sentence with a number, it should be spelled out: “Twenty-seven of the volcanoes ...” But if the number takes a unit (“Two mL of solution was put in each test tube”), then I recommend you rewrite the sentence.

Spacing with mathematical symbols

  • There should be no space between the number and sign: “−1°C,” “1000× magnification.”
  • There should be spaces around the operator in a binary operator “p < 0.005.”

Some codes for special characters

  • En dash: Unicode U+2013, HTML &ndash;, option-hyphen on a Mac
  • Degree symbol: Unicode U+00B0, HTML &deg;
  • Primes and double primes for latitude and longitude: Unicode U+2032 and U+2033, HTML &prime; and &Prime;
  • Minus sign: Unicode U+2212, HTML &minus;
  • Multiplication sign: Unicode U+00D7, HTML &times;
  • How to write typographers’ quotes (smart quotes) in HTML

Scientific names of organisms

See writing scientific names of organisms.

Spacing between sentences

Unless you are writing for a journal that specifies otherwise, use only one space after a period or colon. It will save your publisher from having to remove the extra spaces, and they’ll like you better if you don’t make them do that. If you’re writing for the web or working on a thesis, leave the extra spaces out; they’ll just look awkward and unprofessional.

Text alignment

I suggest aligning your text on the left instead of justifying it. Publishers usually request left alignment in manuscript submissions, and the consistent spacing between words makes it easier to read and edit.

Further references

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