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Chapter 3Chapter 3 Introduction to Quantitative ResearchIntroduction to Quantitative Research

Quantity is the unit of analysisQuantity is the unit of analysis– AmountsAmounts

– FrequenciesFrequencies

– DegreesDegrees

– ValuesValues

– IntensityIntensity

Uses statistics for greater precision and Uses statistics for greater precision and objectivityobjectivity

Based on the deductive modelBased on the deductive model

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Model for Conceptualizing Model for Conceptualizing Quantitative ResearchQuantitative Research

Overall purpose or Overall purpose or objectiveobjective

Research literatureResearch literature

Research questions Research questions and hypothesesand hypotheses

Selecting appropriate Selecting appropriate methodsmethods

Validity and reliability Validity and reliability of the dataof the data

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Creating the Foundation Creating the Foundation for Quantitative Researchfor Quantitative Research

Concept Concept – Abstract thinking to distinguish it from other elementsAbstract thinking to distinguish it from other elements

Construct Construct – Theoretical definition of a concept; must be Theoretical definition of a concept; must be

observable or measurable; linked to other conceptsobservable or measurable; linked to other concepts

Variable Variable – Presented in research questions and hypothesesPresented in research questions and hypotheses

Operationalization Operationalization – Specifically how the variable is observed or measuredSpecifically how the variable is observed or measured

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Research Hypotheses Research Hypotheses for Quantitative Research for Quantitative Research

Educated guess or presumption based on Educated guess or presumption based on literatureliterature

States the nature of the relationship States the nature of the relationship between two or more variablesbetween two or more variables

Predicts the research outcomePredicts the research outcome

Research study designed to test the Research study designed to test the relationship described in the hypothesisrelationship described in the hypothesis

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Quantitative Quantitative Research HypothesesResearch Hypotheses

Directional hypothesisDirectional hypothesis– Precise statement indicating the nature and Precise statement indicating the nature and

direction of the relationship/difference direction of the relationship/difference between variablesbetween variables

Nondirectional hypothesisNondirectional hypothesis– States only that relationship/difference will States only that relationship/difference will

occuroccur

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Assessing HypothesesAssessing Hypotheses

Simply stated?Simply stated?

Single sentence?Single sentence?

At least two variables?At least two variables?

Variables clearly stated?Variables clearly stated?

Is the relationship/difference precisely Is the relationship/difference precisely stated?stated?

Testable?Testable?

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Null HypothesesNull Hypotheses

Implicit complementary statement to the Implicit complementary statement to the research hypothesisresearch hypothesis

States no relationship/difference exists States no relationship/difference exists between variablesbetween variables

Statistical test performed on the nullStatistical test performed on the null

Assumed to be true until support for the Assumed to be true until support for the research hypothesis is demonstratedresearch hypothesis is demonstrated

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Research Traditions Research Traditions in the Use of Hypothesesin the Use of Hypotheses

Hypotheses are always tentativeHypotheses are always tentative

Research hypothesis, not the null Research hypothesis, not the null hypothesis, is the focus of the research hypothesis, is the focus of the research and presented in the research reportand presented in the research report

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Research Questions Research Questions in Quantitative Researchin Quantitative Research

Preferred when little is known about a Preferred when little is known about a communication phenomenoncommunication phenomenon

Used when previous studies report Used when previous studies report conflicting resultsconflicting results

Used to describe communication Used to describe communication phenomenaphenomena

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Types of VariablesTypes of Variables

Variable Variable – Element that is identified in the hypothesis or Element that is identified in the hypothesis or

research questionresearch question

– Property or characteristic of people or things Property or characteristic of people or things that that variesvaries in quality or magnitude in quality or magnitude

– Must have two or more levelsMust have two or more levels

– Must be identified as independent or Must be identified as independent or dependentdependent

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Independent VariablesIndependent Variables

Manipulation or variation of this variable is Manipulation or variation of this variable is the cause of change in other variablesthe cause of change in other variables

Technically, independent variable is the Technically, independent variable is the term reserved for experimental studiesterm reserved for experimental studies

– Also called antecedent variable, experimental Also called antecedent variable, experimental variable, treatment variable, causal variable, variable, treatment variable, causal variable, predictor variablepredictor variable

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Dependent VariablesDependent Variables

The variable of primary interestThe variable of primary interest

Research question/hypothesis describes, Research question/hypothesis describes, explains, or predicts changes in itexplains, or predicts changes in it

The variable that is influenced or changed The variable that is influenced or changed by the independent variableby the independent variable

– In non-experimental research, also called In non-experimental research, also called criterion variable, outcome variablecriterion variable, outcome variable

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Relationship Between Independent Relationship Between Independent and Dependent Variablesand Dependent Variables

Cannot specify independent variables Cannot specify independent variables without specifying dependent variableswithout specifying dependent variables

Number of independent and dependent Number of independent and dependent variables depends on the nature and variables depends on the nature and complexity of the studycomplexity of the study

The number and type of variables dictates The number and type of variables dictates which statistical test will be usedwhich statistical test will be used

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Intervening and Intervening and Confounding VariablesConfounding Variables

Intervening variableIntervening variable– Explains or provides a link between IV and DVExplains or provides a link between IV and DV

– Relationship between the IV and DV can only be Relationship between the IV and DV can only be explained when the intervening variable is presentexplained when the intervening variable is present

Confounding variableConfounding variable– Confuses or obscures the effect of independent on Confuses or obscures the effect of independent on

dependentdependent

– Makes it difficult to isolate the effects of the Makes it difficult to isolate the effects of the independent variableindependent variable

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Operationalizing VariablesOperationalizing Variables

All variables need an operationalizationAll variables need an operationalization

Multiple operationalizations exist for most Multiple operationalizations exist for most variablesvariables

Specifies the way in which variable is Specifies the way in which variable is observed or measuredobserved or measured– Practical and useful?Practical and useful?

– Justified argument?Justified argument?

– Coincides with the conceptual definition?Coincides with the conceptual definition?

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Making the Case Making the Case for Quantitative Research for Quantitative Research

AdvantagesAdvantages

– Tradition and history implies rigorTradition and history implies rigor

– Numbers and statistics allows precise and exact Numbers and statistics allows precise and exact comparisonscomparisons

– Generalization of findingsGeneralization of findings

LimitationsLimitations

– Cannot capture complexity of communication over Cannot capture complexity of communication over timetime

– Difficult to apply outside of controlled environmentsDifficult to apply outside of controlled environments

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Issues of Reliability and ValidityIssues of Reliability and Validity

Reliability = Reliability = consistencyconsistency in procedures and in procedures and in reactions of participantsin reactions of participants

Validity = Validity = truthtruth - Does it measure what it - Does it measure what it intended to measure?intended to measure?

When reliability and validity are achieved, When reliability and validity are achieved, data are free from systematic errorsdata are free from systematic errors

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Threats to Reliability and ValidityThreats to Reliability and Validity

If measuring device cannot make fine If measuring device cannot make fine distinctionsdistinctions

If measuring device cannot capture If measuring device cannot capture people/things that differpeople/things that differ

When attempting to measure something When attempting to measure something irrelevant or unknown to respondentirrelevant or unknown to respondent

Can measuring device really capture the Can measuring device really capture the phenomenon?phenomenon?

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Other Sources of VariationOther Sources of Variation

Variation must represent true differencesVariation must represent true differencesOther sources of variationOther sources of variation– Factors not measuredFactors not measured– Personal factorsPersonal factors– Differences in situational factorsDifferences in situational factors– Differences in research administrationDifferences in research administration– Number of items measuredNumber of items measured– Unclear measuring deviceUnclear measuring device– Mechanical or procedural issuesMechanical or procedural issues– Statistical processing of dataStatistical processing of data