According to the sixth edition of the "Publication Manual of the American Psychological Association," APA format typically applies to papers in the social and behavioral sciences. The manual establishes stylistic guidelines including the use of parentheses to clarify what details stem from research and create easy reading.
Parentheses surround in-text citations: (Sullivan, 2009). Use them to separate extraneous information from the rest of a sentence, such as this example: "(see Figure 2)." Parentheses appear around abbreviations when they first appear, such as "Centers for Disease Control and Prevention (CDC)" and letters that separate items in a list: "The symptoms include (a) rash, (b) fever and (c) incoherence." They also occur around statistical values, t or F degrees and when needed in mathematical formulas, such as "(p=.32)," "t(60=2.27)" and "(x-y)/(x-2)."
- Photodisc/Photodisc/Getty Images