Sometimes I can give an absolute answer because the question is a matter of grammar. For example, it is always wrong to say "neither x or y." It is always correct to capitalize the first letter of a person's name (although you can make exceptions if you like for e. e. cummings and other people who are widely known by a lowercased name). Sentences should always end with a period or question mark.
Grammar is not always this clear-cut. If someone asks me whether a clause should be preceded by "which or "that," I have to ask some questions before I can give an answer. Ditto if someone asks whether "none" takes a single or plural verb; the answer depends on subtleties of meaning.
Some questions, though, have no correct answer. They are matters of style. That is, different publishers or editors do things differently. My answer to, "Should I spell out the number ten?" is, "Who are you writing for?" In Associated Press style, which is used by many periodicals, the numbers ten and above are given as numerals unless they begin a sentence or are a date or a page number. But The Chicago Manual of Style (used for books) has complex rules, and one rule is that the numbers zero through one hundred are spelled out. Scientific style guides have yet more styles for numbers.
Here are a few of the probably thousands of variants of style in American English. All of the following are correct in some publication or another:
- X-ray; x-ray
- 10000; 10,000; 10 000; 104; ten thousand
- 70°; 70° F; 70 °F; 70 degrees Fahrenheit
- 4:30 p.m.; 4:30 pm; 4:30 PM; 1600; four-thirty p.m.
- ten percent; 10 percent; 10%
- Down's syndrome: Down syndrome
- α-interferon, interferon-α, alpha interferon, interferon alpha, IFN-α, interferon alfa
- Look at previous issues of the publication you're writing for.
- If you write for a publication regularly, ask what stylebook they use.
- If you regularly write in a certain academic field, get the stylebooks used in that field, such as those put out by the American Psychological Association, the American Medical Association, the American Chemical Society, and the Council of Science Editors.
- Google different versions of your word or phrase and see how many hits you get for each. Go with the majority.
- If you write often for newspapers or magazines, it makes sense to own the most recent edition of The Association Press Stylebook and Briefing on Media Law. If you write short stories or books, own the most recent Chicago Manual of Style.
- Buy some grammar and general style books so that you can tell whether the question that stumps you is a matter of grammar or a matter of style.
I'll be blogging at Novel Spaces again on September 21. Hope to see you then!