AMA Manual of Style - Stacy L. Christiansen, Cheryl Iverson 2020
Abbreviating Number
Numbers and Percentages
Variable |
Drug |
Placebo |
No. of participants |
49 |
48 |
The word number may be abbreviated No. in the body of tables and line art or in the text when used as a specific designator. Do not use the number sign (#) in place of the abbreviation; this could be confused with the hashtag (#) used in social media. The word number should always be spelled out when it is used as a proper noun (eg, Social Security number).
A No. 10 catheter was placed in the femoral artery.
She was No. 1 in her graduating class.
When referring to numbers of individuals in a study—in tables and figures as well as within parentheses—the abbreviation N is used when referring to the entire sample; n refers to a subsample (see 19.5, Glossary of Statistical Terms).
Patients were enrolled at each study site (N = 2758) and randomly assigned to receive intervention (n = 1378) or placebo (n = 1380).