1Scientific Methods II:Correlational Research• Discuss correlational research• Example: Research on television and aggressionExample of Correct Answer• Hypothesis: Children who play violent video games will behave more aggressively.• IV: Children play either a violent video game or a nonviolent video game• DV: How long kids play with violent (e.g., guns, swords) or nonviolent (e.g., trucks, dolls) toys in a free play situationCorrect Answer (continued)• Ensure internal validity by– Randomly assigning children to the violent vs. nonviolent condition– Keeping experimenters unaware of the kind of game played by the child (to reduce experimenter bias)– Making sure children are not aware of the purpose of the study (to reduce participant bias)• Advantage: Can detect cause and effect relationship• Disadvantage: May not generalize to situations outside of the lab or to all kinds of aggressive behavior2Research Ethics• Lisa Simpson conducts an experiment on Bart and her hamster. Is it ethical? Why or why not?Ethical Issues in Social Psychology• Guideline for Ethical ResearchInformed consent is an agreement to participate in an experiment, granted in full awareness of the nature of the experiment.Deception is misleading participants about the true purpose of a studyDebriefing is explaining to participants, at the end of an experiment, the true purpose of the studyScientific Methods II:Correlational Research• EXAMPLES• "MARRIAGE SLOWS CANCER DEATHS“Evidence that married people have a better chance of surviving cancer than do singles means that the unmarried might be good targets for cancer-prevention programs. Married people with cancer had a 23% higher overall survival rate than the unmarried.3Example 2• Isolation increases with Internet use• Psychologist Robert Kraut and his colleagues report that greater use of the Internet leads to shrinking social support and happiness, and increases in depressionand loneliness…And the findings were unexpected, Kraut says, given that most people use the Internet for chat lines and e-mail, not just to isolate themselves in mounds of electronic information. Example 3“Revenge of the Beaker Bunch”..Researchers Find that Scientists Live LongerIf it were a movie, it would probably be called "Nerds: The Ultimate Revenge.“ A study spanning nearly 70 years suggests that, all else being equal, scientists live longer than non-scientists… According to Friedman'sstudy, nonscientists are 26 percent more likely to die atany given age than scientists. In a sample of 600 menborn around 1912, Friedman's group found that only 67% of nonscientists were still alive by age 70, compared to 72% of the scientists...” Correlational Research• Correlational research examines whether 2 factors are naturally associated. [Co-relation: the degree to which one variable is related to another.]• Examples focus on naturally occurring relationships – marriage & cancer recovery– Internet use & depression– occupation & longevity4Correlations: The Basics• Numerical range: -1.00 to +1.00The Correlational MethodCorrelation CoefficientPositive correlations indicate that an increase in one variable is associated with an increase in the other.Negative correlations indicate that an increase in one variable is associated with a decrease in the other.The Correlational Method5The Correlational Method• SurveysThe correlational method often relies on surveys, as well as on observational data. Surveys are used when the variable of interest is not easily observable.How do we evaluate correlational findings?• Amount use Internet is associated with greater depression. Why?• 3 possible explanations• Using Internet Æ depression • Depression Æ greater Internet use (cannot determine direction of causality)•A 3rdvariable might be related to both using the Internet and becoming depressed3rdVariables• People with few friends may be more likely to spend time on Internet and to become depressed• People w/low self-esteem may use Internet (to avoid rejection) and are at risk for depression6Evaluating CorrelationalResearch• Correlational research cannot determine causality.• Problems knowing direction of causality• Problems knowing whether some 3rdvariable (confounding variable) might explain the observed correlationHow do we evaluate correlational findings?• Consider in context of research on TV exposure and aggression• Start w/theoretical idea and to test specific hypotheses. • Hypothesis: Children who watch more violent television shows behave more aggressively.TV & Violent Content• 8 out of 10 Sat. morning programs contain violence• Sat. morning children’s shows: 20 violent acts per hour• Average American watches 4 hrs of TV per day, or over 1000 hrs. per year.• What is relationship between watching TV and children’s aggressive behavior?7TV and Aggression• Many studies• Sample correlational paradigm:– Parents record how much TV their kids watch– Teachers record aggressive behaviors (hitting, pushing, shoving, insulting, etc.)IV AND DV in CorrelationalResearch• Quasi-Independent Variable: how much TV kids watch (*not* manipulated, but acts like IV)• Dependent Variable: amount of aggressive behavior at schoolTV and Aggression: Correlational Studies• Conclusion: Children who watch TV that includes violent content are more likely to behave aggressively.8Why?• Theory: Watching TV causes aggression• But: Maybe more aggressive kids are attracted to watching violence on TV (direction of causality)•Or: A 3rdvariable might account for the relationshipThird Variables• What are some possible third variables that could explain the correlation between watching TV and aggressive behavior?Marriage and Surviving Cancer• Direction of causality is not as much of a problem (unlikely that surviving cancer caused marriage!)• What are some 3rdvariables that could account for the greater survival rate of married individuals?9Disadvantage• Correlation cannot determine causality• Even if we measure possible third variables (e.g., measure eating habits, measure health care, etc.) and use statistical techniques to “control” for them, we still cannot be sure about the cause-and-effect relationship.Then…Why do correlationalresearch?• Allows for the study of problems that would be difficult to study in the lab • Can’t manipulate who is married or not, who has a stressful job or not,