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

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