Periods are the most common end-of-sentence punctuation marks. Use a period at the end of a declarative or imperative sentence and at the end of each table footnote and each figure legend.
Advances in medical technology have saved many lives.
Always listen carefully.
Also use a period after a rhetorical question (one not requiring an answer).
Where, indeed, is the Osler of today.
The period precedes ending quotation marks and reference citations.
The child is rated in 7 areas, such as “accepts responsibility” and “interacts appropriately with peers.”
We followed the methods of Wilkes et al.5
The period follows a closing apostrophe:
Their data were inconsistent with their associates'.
Use a period after the arabic numeral when enumerating paragraphed items.
The signed authorship form required by the journal included the following sections:
1. Authorship responsibility, criteria, and contributions
2. Data access and responsibility
3. Financial disclosure
4. Acknowledgment statement
(See also 19.5, Numbers and Percentages, Enumerations, and the Enumerations section in 8.2.2, Semicolon, for examples of ways to handle enumerations that are run into the text or that are set off with bullets.)
Use the period as a decimal indicator. (See 19.7.1, Numbers and Percentages, Forms of Numbers, Decimals.)
r = 0.75
P < .05
The period in raised position indicates multiplication. (See also 18.2.2, Units of Measure, Expressing Unit Names and Symbols, Products and Quotients of Unit Symbols, and 21.6, Mathematical Composition, Expressing Multiplication and Division.)
When Not to Use a Period.
JAMA and the Archives Journals do not use periods with honorifics (courtesy titles), scientific terms, and abbreviations (exceptions: No. for “number” and St. when it is part of a person’s name, although no period is used with St in a city name, eg, St Louis, Missouri) (see 2.1, Manuscript Preparation, Titles and Subtitles; 2.2, Manuscript Preparation, Bylines and End-of-Text Signatures; and 14.0, Abbreviations).
George Hussey, MD
George R. Hussey, MD