1. Numbers Abbreviations and Acronyms
Numbers expressed in numerals and numbers expressed in words
In this lesson, we will focus on how to express numbers in APA style.
Reference material:
American Psychological Association. (2010). Publication manual of the American Psychological Association (6th ed.). Washington, DC: Author.

2. Use Words for: Numbers less than 10 Common fractions
five participants
two experiments
Common fractions
one third of the members of the first group
a two-thirds majority
Numbers that start a sentence
Three different conditions were tested.
Fifty college students participated in the study.
Universally accepted usage
The Twelve Apostles
Five Pillars of Islam
We use words to express numbers less than 10, numbers that start a sentence, and universally accepted usage. EXCEPTIONS can be found on the following slides.

3. Use Numerals for: Numbers 10 and above
65 items
10 points
The 13th participant
Numbers in the abstract of the paper (except to start a sentence)
Numbers preceding a unit of measurement or time
5 cm
12 lbs
3 min
6 weeks

4. Numerals (continued)
Numbers that are used as fractions (except common fractions), decimals, percentages, ratios, and percentiles
3/16
75% of the population
A ratio of 10:1
The 95th percentile

5. Numerals (continued)
Numbers that represent time, date, age, scores and points on a scale
Lunch is at 12:30 p.m.
2-year-olds
A score of 5 on a 10-point scale
A 5-point scale ranging from 1 (not at all) to 5 (extremely)
June 13th
Numbers that represent a specific place in a series
Condition 1, Condition 2, Condition 3, etc.
Group 5, Group 6, Group 7, etc.
Participant 12, Participant 13, Participant 14, etc.
Note that the word representing the series (e.g., condition, group, level, floor, etc.) should be capitalized when it represents an item in the series, but not when it is used generically:
All of the groups went on the trip, but Group 1 left at noon, Group 2 left at 1:00 and the other groups left at 2:00.
Please take special note of the format for describing a scale, including the italicized descriptors inside parentheses.

6. Abbreviations
Abbreviations that are pronounced one letter at a time (e.g., APA, DSM, BDI, IQ) are called initialisms
Abbreviations that are pronounced as a word are called acronyms (e.g., AIDS)
Abbreviations should be used sparingly. Use them when:
1. The abbreviation is standard and it will not interrupt the reader’s understanding (e.g., AIDS)
2. If space can be saved and repetition can be avoided with the use of the abbreviation
The word acronym is commonly used to refer to both acronyms (abbreviations formed from the first letters of the name and pronounced as a single word) and to initialisms (abbreviations formed from the first letters of the name a pronounced one letter at a time).
Abbreviations that do not need an explanation in text are those that can be found in Merriam-Webster’s Collegiate Dictionary as word entries. This means that the word, when looked up in the dictionary, will not be labeled abbr.
The APA Manual advises you to use an initialism or acronym only if it comes up at least three times in the paper. Even then, if the instances are far apart and the reader would have to search to recall what the acronym means, it is not advisable to use one.

7. Use of Initialisms & Acronyms
Use the full term the first time, followed immediately by the initialism or acronym in parentheses (include any necessary citation within the same parentheses, separated by a semi-colon)
Human immunodeficiency virus (HIV)
Beck Depression Inventory (BDI; Beck, Ward, Mendelsohn, Mock, & Erbaugh, 1961)
Do not use the full term in your paper after this point.

8. Examples
My first group of participants would exercise in a peppermint-scented room, after which they would complete the State form of the State-Trait Anxiety Inventory (STAI; Spielberger, Gorsuch, & Lushene, 1970).
According to the American Psychological Association (APA), abbreviations can help shorten a paper; however, the APA suggests avoiding abbreviations that may confuse your reader.

9. Common Abbreviations Latin abbreviations: Units of time:
cf. e.g., i.e., viz., vs. etc.
Units of time:
s min hr ms ns
Units of measurement:
a.m. ˚C cm ˚F g Hz in. kg
L m ml mm p.m. V W
Do not add an s after any abbreviation of a unit of measurement
Latin abbreviations: cf compare
e.g., for example, i.e., that is,
viz namely,
vs versus etc and so forth
Exception: In the reference section and when referring to court cases, use v. for “versus” instead of vs.
Students often confuse e.g. with i.e., but they mean quite different things (see above). Only use them parenthetically; used within the body of the sentence, they must be written out as for example or that is.
Abbreviate units of time less than one day (do not abbreviate day, week, month, or year). Think of day as the cutoff; you don’t abbreviate it because it’s already short. You do abbreviate units of time shorter than a day, but not longer.
a.m. ante meridiem
˚C degree Celsius
cm centimeter
˚F degree Fahrenheit
g gram
Hz hertz
in inch (include metric equivalent in parentheses)
kg kilogram
L liter
m meter
ml milliliter
mm millimeter
p.m. post meridiem
V volt
W watt * Exception: Do not add an s after any abbreviations of units of measurement. Incorrect: 20 cms, 5 Ls, 10 in.s Correct: 20 cm, 5 L, 10 in. ** Exception: To form the plural of p. (page), write pp.
Many more abbreviations for units of measurement can be found on p. 109 of the APA Manual.

10. Examples I like many fruits (e.g., strawberries, grapes, cantaloupe).
She defected from the relationship (i.e., she left him).
The participants had 5 hr to complete the task.
Each mouse in Group 2 received 3 g of the experimental drug.
Units of time are very commonly mentioned in APA style writing, so please take careful note of how to use them. Units of time shorter than a day are abbreviated and do not take a period. They also do not take an s, even when they refer to more than one unit. To remember how to abbreviate units of time properly, I suggest practicing the mantra:
"No s, no period."