Show Summary Details
Page of

Reporting Proportions and Percentages 

Reporting Proportions and Percentages
Numbers and Percentages

Stephen J. Lurie

and Margaret A. Winker

Page of

PRINTED FROM AMA MANUAL OF STYLE ONLINE ( © American Medical Association, 2009. All Rights Reserved. Under the terms of the license agreement, an individual user may print out a PDF of a single chapter of a title in AMA Manual of Style Online for personal use (for details see Privacy Policy and Legal Notice).

Subscriber: null; date: 27 May 2018

Reporting Proportions and Percentages

Whenever possible, proportions and percentages should be accompanied by the actual numerator (n) and denominator (d) from which they were derived. The numerator and denominator should be expressed as “n of d,” not by the virgule construction “n/d,” which could imply that the numbers were computed in an arithmetic operation.

Death occurred in 6 of 200 patients.

Not: Death occurred in 6/200 patients.

For clarity, when a numerator and denominator are accompanied by a resulting proportion or percentage, the proportion or percentage should not intervene between the numerator and denominator.

Death occurred in 6 of 200 patients (3%).

Death occurred in 3% (6 of 200) of patients.

Of the 200 patients, death occurred in 6 (3%).

Of the 200 patients, 6 (3%) died.

Not: Death occurred in 6 (3%) of 200 patients.

The denominator may be omitted if it is clear from the context.

Death occurred in 3 patients (1%).

In expressing a series of proportions or percentages drawn from the same sample, the denominator need be provided only once.

Of the 200 patients, 6 (3%) died, 18 (9%) experienced an adverse event, and 22 (11%) were lost to follow-up.

Previous | Next