VARIABLESVARIABLES• 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

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

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

“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)

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

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

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

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?)

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

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

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

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.

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?

Relationships among variables

• Differences– Differences in kind, degree

• Relationships (correlations)– Positive correlation– Negative correlation– No or neutral correlation