1. VARIABLES
Definition: Variables are properties or characteristics of people or things that vary in quality or magnitude from person to person or object to object (Miller & Nicholson, 1976)
Demographic characteristics
Personality traits
Communication styles or competencies
Constructs
in order to be a variable, a variable must vary (e.g., not be a constant), that is, it must take on different values, levels, intensities, or states

2. Definitions
Variable: “any entity that can take on a variety of different values” (Wrench et al, 2008, p. 104)
gender
self-esteem
managerial style
stuttering severity
attributes, values, and levels are the variations in a variable
Attribute: political party:
Value: Democrat, Republican, Independent, etc.
Attribute: Self-esteem
Level: High, Medium, Low

3. independent variable
the variable that is manipulated either by the researcher or by nature or circumstance
independent variables are also called “stimulus” “input” or “predictor” variables
analogous to the “cause” in a cause-effect relationship

4. “operationalization” of the independent variable
Operationalization: translating an abstract concept into a tangible, observable form in an experiment
Operationalizations can include:
variations in stimulus conditions (public schools versus home schooling)
variations in levels or degrees (mild vs. moderate vs. strong fear appeals)
variations based on standardized scales or diagnostic instruments (low vs. high self esteem scores)
variations in “intact” or “self-selected” groups (smokers vs. non-smokers)

5. varieties and types of variables
Discrete variables
Nominal variables: distinct, mutually exclusive categories
religions; Christians, Muslims, Jews, etc.
occupations; truck driver, teacher, engineer
marital status; single, married, divorced
Concrete versus abstract variables
concrete; relatively fixed, unchanging
biological sex
ethnicity
abstract; dynamic, transitory
mood, emotion
occupation
Dichotomous variables:
true/false, female/male, democrat/republican
Ordered variables: mutually exclusive categories, but with an order, sequence, or hierarchy
fall, winter, summer, spring
K-6, junior high, high school, college

6. varieties and types of variables--continued
Continuous variables: include constant increments or gradations, which can be arithmetically compared and contrasted
IQ scores
self-esteem scores
age
heart rate, blood pressure
number of gestures

7. Unit of analysis Definition: The specific entity being examined
individual; self esteem, fluency
dyad: self disclosure, touch
group: roles, norms
Organization: communication networks, upward-downward influence
Culture: individualism vs. collectivism
What constitutes a specific score or measure on the outcome variable?
marital satisfaction?
one row of data in SPSS
Ecological fallacy: drawing conclusions about individuals based on group data
committing a “sweeping generalization” about participants in a research study
individualism/collectivism
all southerners are bigots

8. operationalization
definition: the specific steps or procedures required to translate an abstract concept into a concrete, testable variable
example: high versus low self-esteem (split-half or top vs. bottom third?)
example: on-line versus traditional classroom (how much e-learning constitutes an “on-line” class?)

9. examples of operationalizations
credibility (high versus low)
culture/ethnicity (self-report)
type of speech therapy (in-clinic vs. at school, vs. at home)
compliance-gaining strategy preferences (positive versus negative, self-benefit versus other benefit)
“powerless” language style
fear appeals (mild, moderate, strong)
food server touch versus no touch

10. dependent variable
a variable that is observed or measured, and that is influenced or changed by the independent variable
dependent variables are also known as “response” or “output” or “criterion” variables
analogous to the “effect” in a cause-effect relationship

11. confounding variable
also known as extraneous variables or intervening variables
confounding variables “muddy the waters”
alternate causal factors or contributory factors which unintentionally influence the results of an experiment, but aren’t the subject of the study

12. mediating variable
a.k.a. moderating, intervening, intermediary, or mediating variables
a 2nd or 3rd variable that can increase or decrease the relationship between an independent and a dependent variable.
for example, whether listeners are persuaded more by the quality or quantity of arguments is moderated by their degree of involvement in an issue.

13. interchangeability of independent and dependent variables
The same concept or construct could serve as the independent variable in one investigation, and the dependent in another.
example: “source credibility”
as an independent variable; RQ: Does source credibility (low versus high) have a significant effect on attitude change?
As a dependent variable; RQ: Does the amount of evidence contained in a speech affect listeners’ perceptions of the source’s credibility?
example: “fetal alcohol syndrome” (FAS)
As an independent variable: RQ: Does severity of FAS correlate positively with language delay in infants?
As a dependent variable: RQ: Does the amount of maternal alcohol use correlate positively with the severity of FAS in infancy?

14. Relationships among variables
Differences
Differences in kind, degree
Relationships (correlations)
Positive correlation
Negative correlation
No or neutral correlation