COMM 301: Empirical Research in Communication

1. COMM 301:Empirical Research in Communication Lecture 11 (Continuation from Lect10) Kwan M Lee

2. Remember 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.

3. Number of independent variables • Single factor studies • Examine one independent variable at a time • All previous designs are single factor studies • Factorial studies

4. Number 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)

5. Different 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 project

6. Issues in practice • Ensure group equivalence • Random assignment, etc. • Manipulation check • Control all possible intervening variables through detailed protocols • Procedures • Space • Data storage • Pretest if necessary

7. Kwan’s Practical Guidelines for Experimental Research

8. Basic Structure of Research • Research question • Operationalize study • Run subjects • Look at data • Present to world!!!

9. Research 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)

10. What 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 X

11. What 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 questions

12. Where do Ys come from? • Questionnaire • Web • Paper and pencil • Telephone

13. Where 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? • Smiles

14. How many Ys? • The more, the merrier • Put items together • More error-free • More stable • At least one non-attitudinal item is important

15. Operationalizing the Study • Instantiate the Xs • Pick framing • Buying • Learning • Disclosure • Entertainment • Collaboration • Assessment • Competition

16. Operationalizing the Study (cont.) • Pick modality • Web • Phone • Lab • Field • These three (instantiation, framing, modality) are determined iteratively

17. Running Subjects • Subject criteria • Gender should be always balanced if possible • Balance

18. Analysis • T-test • ANOVA • ANCOVA • Etc….

19. Present the Research! • Write up! • Millions of friends and admirers