« Announcing New Features on the APA Style Blog | Main | Five Steps to a Great Title »

July 01, 2010

A Post About Nothing

Timothy McAdoo by Timothy McAdoo

Today I want to zero in on a special topic. This is not just an empty set of words: Let’s de-cipher another APA Style point!

The zero before a decimal point is known as a leading zero. Have you noticed that sometimes this zero is used in decimal values and sometimes it is not?

APA Style has a very simple guideline for leading zeros:

  • If a value has the potential to exceed 1.0, use the leading zero.
  • If a value can never exceed 1.0, do not use the leading zero.

Thus, because most units of measure have the potential to exceed 1.0, the leading zero is frequently needed. A value over 1.0 does not need to actually appear in the text. Here are just a few examples:

…was 0.75 in. tall by 0.95 in. wide.

Participants viewed, on average, less than 0.65 hr of the footage.

…had means of 1.01, 2.21, and 0.95, respectively.

…had 95% CIs [0.62, 1.12], [-2.44, 4.30], and [-3.19, -2.39], respectively.


There are some values that by definition can never exceed 1.0. The omission of the leading zero is a visual indicator of this restricted range. The most common cases are p values and correlations:

…was significant (p < .01).

…was significant (p = .001).

…was shown to be highly correlated (r = .71).


A consistent presentation of statistical values, both within a paper and across published articles, provides a visual symmetry that can help readers focus on content over form.

I hope this zippy post has helped nullify any confusion. If you’re still drawing a blank, you can also find this guideline and additional examples on page 113 of the Publication Manual of the American Psychological Association (6th ed.).

TrackBack

TrackBack URL for this entry:
http://www.typepad.com/services/trackback/6a01157041f4e3970b0133f1fd1e2d970b

Listed below are links to weblogs that reference A Post About Nothing:

Comments

Search the APA Style Blog


ABOUT THE BLOG

My Photo


About Us

Blog Guidelines

APA Style FAQs

Archives


rss Follow us on Twitter

American Psychological Association APA Style Blog

Twitter Updates