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9/13/2011 1 Five Steps of the Scientific Method Developing a hypothesis Performing a test G th i bj ti d ta er ng o ec ve a a Analyzing the results Publishing, criticizing, and replicating the results Developing a hypothesis Performing a test Gathering Hypothesis ? A statement predicting the outcome of a scientific study Testable description of Five Steps of the Scientific Method objective data Analyzing the results Publishing, criticizing, and replicating the results ? relationship between events Sources of Hypotheses ? Naturalistic Observation ? Strong real-world applicability; but? ? Uncontrolled ?Can?t know what other influences are at work ?Risk of observer bias ? Case Studies ? Rich detail about individuals and access to rare phenomena; but? ? Uncontrolled ? Problem of generalizability The Value of Case Study ? Kim Peek: Savant Developing a hypothesis Performing a test Gathering Five Steps of the Scientific Method Study Design ? Survey ? Correlational study objective data Analyzing the results Publishing, criticizing, and replicating the results Operational definitions Variables specified and defined in measurable terms ? Experiment Developing a hypothesis Performing a test Gathering Data Five Steps of the Scientific Method objective data Analyzing the results Publishing, criticizing, and replicating the results Information gathered by a researcher and used to test a hypothesis 9/13/2011 2 Developing a hypothesis Performing a test Gathering Five Steps of the Scientific Method objective data Analyzing the results Publishing, criticizing, and replicating the results Based on statistical analyses of results, the hypothesis is accepted or rejected Developing a hypothesis Performing a test Gathering Five Steps of the Scientific Method objective data Analyzing the results Publishing, criticizing, and replicating the results Peer review Critique by other researchers Replication Repetition to see if the same results are found Survey Research ? Population ? Entire group of interest to researchers to which they wish to generalize their findings ? Sample ? Part of a population that is studied in order to reach conclusions about the entire population ? Representative sample ? Sample that mirrors the population of interest ? Includes subgroups in the same proportion as found in the population Survey Research ? Random selection of subjects to obtain a representative sample ? Self-report measures ? Interviews ? Questionnaires ? Strengths ? Allows description of population ? Efficient and less costly ? Limitations ? Sample versus Population ? Self-report biases Experimental Research ? Systematically vary an aspect of the situation, control all others, and observe (measure) the effects to establish a ca se and effect relationshipu - - ? Variable: a characteristic that varies ?Must have at least two values ?Male or Female ?Can have a virtually infinite number of levels ?Self-esteem?very low to very high and everywhere in between Elements of the Experiment ? Independent variable ? The variable the researcher manipulates ? The cause in the cause and effect - - relationship ? Dependent variable ? The variable the researcher measures ? The effect in the cause-and-effect relationship 9/13/2011 3 The Logic of Experimentation Variable Variable Variable Variable Variable Dependent Variable What causes change in this phenomenon? Does violence on television encourage aggressive behavior in viewers? ? Independent variable? ? Violent TV ? Dependent variable? ? Aggressive behavior Does violence on television encourage aggressive behavior in viewers? ? Operational definition for the IV? ? Exposure to X hours of TV shows portraying violent behavior ? Operational definition for the DV? ? Given a frustrating task to complete, how many? ?Aggressive verbalizations? Aggressive acts? Elements of the Experiment ? Eliminating Confounding Variables ? Random assignment of subjects ?Experimental group(s) ?Control group ?Subjects exposed to the experimental environment but not the IV ?Minimize ?expectancy effects? ?Subjects (?single blind?) ?Subjects and Experimenters (?double-blind?) Does violence on television encourage aggressive behavior in viewers? ? If similar people watch different programs under comparable conditions, then will those who watch more violent programs become more aggressive? The Logic of Experimentation Variable Independent Variable Variable Variable Variable Dependent Variable All possible causes except one are controlled 9/13/2011 4 The Logic of Experimentation Variable Independent Variable Variable Variable Variable Dependent Variable Any effects on the DV must be caused by the IV Correlational Research ? ?Natural experiments? ? To what extent are two variables related? f C? Features o a orrelation ? Direction ? Strength Direction of the Correlation ? Positive correlation ?When high values of one variable are associated with high values of another variable ?Vary in the same direction ? Negative (inverse) correlation ?When high values of one variable are associated with low values of another variable ?Vary in opposite directions Direction of the Correlation Negative None Positive Strength of the Correlation ? How close is the relationship? ? How accurate is the prediction? P f? er ect ? High ? Moderate ? Weak Measuring Correlation ? Correlation coefficient (r) no relationshipstrongest strongestiti 0-1 +1 negative pos ve 9/13/2011 5 Correlational Research ? Strengths ? Study phenomena that cannot be studied experimentally ? Limitations ? Correlation does not imply causation ?Can predict relationships, but not tell why/how ? Uncontrolled ?Confounding (?third?) variables ?Shoe size and math skills in school-age children ??Our graduates earn 40% more!? Does violence on television encourage aggressive behavior in viewers? Are people who watch more violent television programs more likely to behave aggressively themselves? Maybe watching violent television makes people more aggressive? Maybe there is something else that causes people to Correlation and Maybe aggressive people like to watch more violent television? watch more violent television and to become more aggressive? Causality zuckofa Microsoft PowerPoint - IntroResearchSlidesZuckoff