Is there a rule to rather use points and not commas as decimal separators in academic writing?

Question

I am from Europe and always use a comma as a decimal separator. Thus, in all previous publications I have used a comma as a separator, noone ever objected. We recently submitted a new manuscript and one reviewer comment we got was that we should use points instead of commas as separators. The article was written in English; the journal has a style guide but the separator issue is not covered.

Personally, I think this request is weird, as both versions are widely used and not, like non-SI units limited to very few countries. Also, I don't think that anyone will mistake 2,34 mm as anything other than what it is supposed to mean, even if they would rather write 2.34 mm instead.

So my question is: is there an (unwritten) rule about that point instead of commas should be used as separators in academia that I don't know about or is the reviewer simply trying to change the data formatting to their own preference?

Answer 1

(You did not specify the language of the paper, so I am going to assume that it is written in English.)

There is no rule that in academia points must be used instead of commas.

There is, however, a rule that in English the point rather than the comma is used. If you are writing your paper in English, then you should use the point, for exactly the same reasons that you should write quotations "like this" instead of writing them «like this». (More precisely, this seems to hold in every variety of English except for South African English.)

The fact that you feel inclined to use the comma rather than the point is more a question of you importing the conventions of your own language into English, not a clash between your personal preference and the referee's. It's not substantially different from a French person being inclined to write quotations «like this» or a German person being inclined to write "I think, that this is true" with the extra comma.

Of course, this works both ways. If you are writing a paper in German or Turkish, then you should use the decimal comma.

(Beware that I do not work in a field where decimal separators are used on a regular basis, though.)

Answer 2

The ISO 80000-1:2013 standard allows the use of either "." or "," as a decimal point, but not a mixture of the two in the same document. It also says one should never use either of them as a thousands separator (the correct character to use as a thousands separator being a thin space).

Answer 3

In American, British, and Canadian English, the decimal separator should be a point, not a comma. The Chicago Manual of Styles says the decimal point is represented by a comma in European countries except Great Britain (16th edition, rule 9.20). The trouble is that in US and British English, a comma is used to separate groups of three digits (e.g., 12,345.00), and therefore it should not also be used as a decimal separator. Not being able to unambiguously interpret 37,012 would be a major snafu.

The Chicago Manual of Style is followed by a great many publishing houses. It also says (rule 9.56) that in SI units, "thin, fixed spaces rather than commas are used to mark off groups of three digits", which removes the ambiguity I just pointed out. Nevertheless, the rule is clear, and US undergraduate students correct me if I use the wrong symbol for a decimal separator.

Answer 4

If the journal has no preference mentioned then I would stick with the customary one for the country of the journal. Much like you would use British-English for UK publications and American-English for USA ones (unless otherwise stated).