COMM 301: Empirical Research in CommunicationRemember the last lectureNumber of independent variablesNumber of independent variables (cont.)Different or Same Subjects in CellsIssues in practiceKwan’s Practical Guidelines for Experimental ResearchBasic Structure of ResearchResearch QuestionsWhat are X1 and X2What are the Ys?Where do Ys come from?Where do Ys come from? (cont.)How many Ys?Operationalizing the StudyOperationalizing the Study (cont.)Running SubjectsAnalysisPresent the Research!11COMM 301:Empirical Research in Communication Lecture 11 (Continuation from Lect10)Kwan M Lee22Remember the last lecture•Experimental research designs are categorized along four dimensions–Research settings–Amount of control–Number of independent variables–Different subjects vs. Same subjects in cells•We will talk about the third and fourth dimensions.33Number of independent variables•Single factor studies–Examine one independent variable at a time–All previous designs are single factor studies•Factorial studies44Number of independent variables (cont.)•Factorial (multiple factors) studies–Study simultaneous impact of two (or more) independent variables (factors) on dependent variables–Investigate both main effects and the interaction effects–Factorial design statement•e.g. 3 X 2 Design (three by two factorial design)•3 levels of IV 1 (e.g., violence in film: H M L)•2 levels of IV 2 –(e.g., gender)Cell55Different or Same Subjects in Cells–Between•Each cell has a separate group of participants•Comparisons made between the cells•Typically more than 12 per cell–Within•Subjects go through all treatment levels•Repeated measures–Mixed–Focus on the between-subject design for the project66Issues in practice–Ensure group equivalence•Random assignment, etc.–Manipulation check–Control all possible intervening variables through detailed protocols•Procedures•Space•Data storage–Pretest if necessary77Kwan’s Practical Guidelines for Experimental Research88Basic Structure of Research•Research question•Operationalize study •Run subjects•Look at data•Present to world!!!99Research Questions•What is the causal relationship between:X1 and Y1, Y2, … , Yn(variable) (variables)X2 and Y1, Y2, … Yn, Yn+1, Yn+2…(variable) (variables)1010What are X1 and X2•Manipulate one and only one thing•2 or 3 “levels” each–Different kinds of something–With vs. without something•Independently manipulable•Randomly assigned–Balance is o.k.•Each person gets only one level of each X1111What are the Ys?•Must vary•Continuous or Dichotomous–Continuous•“On a scale of 1-10”•“How many times did they smile?”•“How much did they bid?”•“What was the score of the game?”–Dichotomous•“Vote for one of A or B”•“Did you win or lose?”•Yes/No questions1212Where do Ys come from?•Questionnaire–Web–Paper and pencil–Telephone1313Where do Ys come from? (cont.)•Observation–What do people do with the interface?•Performance•Engagement–What do people cognize?•Memory•Learning–What do people say?•How many words?•How many adjectives?–How do people look?•Smiles1414How many Ys?•The more, the merrier•Put items together–More error-free–More stable•At least one non-attitudinal item is important1515Operationalizing the Study•Instantiate the Xs•Pick framing–Buying–Learning–Disclosure–Entertainment–Collaboration–Assessment–Competition1616Operationalizing the Study (cont.)•Pick modality–Web–Phone –Lab–Field•These three (instantiation, framing, modality) are determined iteratively1717Running Subjects•Subject criteria–Gender should be always balanced if possible–Balance1818Analysis•T-test•ANOVA•ANCOVA•Etc….1919Present the Research!•Write up!•Millions of friends and