Ever get confused when using statistical terms? You’re not alone. In writing for the social sciences in particular, the worlds of mathematics and grammar collide. Academic authors not only have to run statistical tests, but discuss the results in a clear and cohesive way—and since you can lose marks or have a paper rejected from a journal for poor use of English, getting these terms grammatically correct is key. Below are a few common statistical abbreviations, and how they should appear in singular versus plural form.
| Written-out Form | Abbreviation/Symbol | ||
| Singular | Plural | Singular | Plural |
| Cohen’s d | Cohen’s ds | d | ds |
| degree of freedom | degrees of freedom | df | dfs |
| F statistic or F value | F statistics or F values | F | Fs |
| mean | means | M | Ms |
| sample size (subsample) | sample sizes (subsample) | n | ns |
| sample size (full sample) | sample sizes (full sample) | N | Ns |
| p value | p values | p | ps |
| r value | r values | r | rs |
| R2 value | R2 values | R2 | R2s |
| standard deviation | standard deviations | SD | SDs |
| standard error | standard errors | SE | SEs |
| t value | t values | t | ts |
| z score | z scores | z | zs |
| Cronbach’s alpha | Cronbach’s alphas | Cronbach’s α | Cronbach’s αs |
| beta | betas | β | βs |
| chi-square | chi-squares | χ2 | χ2s |
| delta | deltas | Δ | Δs |
Source: http://blog.apastyle.org/apastyle/statistics/
Although the above information is based on APA preferences, for some plural abbreviated forms many publishers and institutions would prefer that you write, for example, “Cronbach’s α values” rather than “Cronbach’s αs,” as the latter version could lead to confusion. If you’re not sure which to use, that’s definitely something we can help with.
When deciding between using the singular or plural form of a statistical abbreviation, it’s important to refer to the syntax of your sentence (again, we can help make sure your plurals are perfect!). When using plural abbreviated forms, add a lowercase “s” to the end of the abbreviation, but don’t add an apostrophe before or after the “s” (it’s not “Cronbach’s α’s,” for example) and don’t italicize or capitalize the “s” either—just a simple “s” will do.
Understanding how and when to correctly use statistical terms in your paper, thesis, or dissertation can be headache-inducing, so a professional academic editing service can be invaluable. At Stickler, we have over a decade of experience editing statistical analyses, and we understand the conventions expected by journals and research institutions. Contact us today and let us help you sort your ps from your SEs!