Numbers Anyone?

by Paige Jackson

We have been heartened by the volume and thoughtfulness of the questions and suggestions we’ve received on the APA Style Blog, and we’re always looking for ways to help writers learn more about APA Style.  We thought it might be useful to follow up on last week’s guest post by Tony Onquegbuzie and colleagues about what they found to be the most common APA Style errors.  Their data were based on the fifth edition of the APA Publication Manual, but most of the style rules cited remained unchanged in the sixth edition.  So, we thought it might be helpful to focus some of our upcoming posts on Onwuegbuzie and colleagues’ “Top 60.”

Top on that list are APA Style rules related to the use of numbers.  We have devoted a number of blog posts to this topic.  Below we expand on those that Onwuegbuzie and colleagues found to be especially challenging.

1.    Use numerals to express numbers 10 and above, and use words to express numbers below 10 (see sections 4.31–4.32, pp. 111–112).

This general rule was altered slightly from the fifth to the sixth edition of the Publication Manual.  The fifth edition required that when numbers below 10 are grouped for comparison with numbers 10 and above within the same paragraph, all numbers so grouped would be expressed in numerals.  However, per the sixth edition, the general rule holds regardless of items that are grouped for comparison.  So, it’s now fine to say, “Of the snakes, 13 were poisonous and nine were harmless garter snakes.”

2.     Use numerals to express units of time, dates, ages, and numbers that denote a specific place in a numbered series (see section 4.32, p. 112).

This general rule about using numerals in these contexts is the same as in the fifth edition.  Note two related changes, however:

• The fifth edition specified that numerals should be used when discussing numbers of subjects or participants in an experiment.  The sixth edition does not contain that rule, so the general rule about expressing numbers 10 and above with numerals and below 10 with words holds.  Correct usage per the sixth edition would be, “The control group contained 17 participants, nine of whom were female and eight of whom were male” (see related blog posts).
• There is also a new exception in the sixth edition—that words should be used to express units of time when those units are approximate:  “It took the rats about three seconds to discover the new food source.”

Are there APA Style rules on numbers that seem mystifying (or perhaps illogical!)?  Let us know, and we’ll try to  clarify them.