Bài giảng Chapter 8 Quantitative Research Designs

The Experimental Framework Used to determine causation Conducted in lab or other controlled setting To control for extraneous influences Independent variable is manipulated by researcher Participants randomly assigned to conditions or treatments

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Chapter 8 Quantitative Research Designs1The Experimental Framework Used to determine causationConducted in lab or other controlled setting To control for extraneous influencesIndependent variable is manipulated by researcherParticipants randomly assigned to conditions or treatments2The Classical ExperimentResearcher controls Selection of treatment & control groups – based on theoryRandom sampleRandom assignment of participants to conditions – ensures participants in each condition are equivalent before any treatmentManipulation checks3Posttest Experimental Design4Pretest-Posttest Experimental Design5Factorial Experimental DesignTreatment groups based on two or more independent variablesDependent variable measured once after treatment givenCan test for main and interaction effects6Longitudinal Experimental DesignsMultiple measurements of the dependent variable across timeTime between measurements depends on the nature of the communication phenomenon studiedUsed for studying training effects or degree of retention7Evaluating Experimental DesignStrengthsResearcher controls manipulation of IV and random assignment to conditionAssumes that any effect on DV is the cause of the IVPrecisionLimitationsNot all communication can be studied using experimentsOther external influence may be the cause of DV changeMay not reflect reality8Quasi-ExperimentsResearcher relies on natural variation of independent variablePosttest, pretest-posttest, factorial, and longitudinal designs can be usedIncludes field experiments in which communication is studied in context9Descriptive DesignsAlso called cross-sectional or non-experimental studiesResearcher does not control manipulation of IVParticipants not randomly assigned to conditionsPredictor and criterion are better labels for IV and DV as they do not imply causality10Researcher Effects and Procedural BiasIntroduced in interaction with participantsSimilarity of researcher to participantsHow researcher communicates to participantsResearcher unknowingly encourages desired responsesDemand characteristics created when topic has socially desirable elementsUse research protocol to detail procedural steps11Comparing Research Designs12