Research Methods Learning How We Know What We Know
Why Scientific Method is Important • Avoids pitfalls in human logic: • Human intuition • Hindsight bias • Overconfidence • Confirmation bias • False consensus effect • Promotes critical thinking & healthy skepticism • Allows for stronger, more reliable conclusions to be drawn
Descriptive Methods • Goal: Describe behavior, and that’s it. • Two main types of descriptive methods: • Naturalistic Observation • Researchers do not intrude on the natural behaviors • Avoids Hawthorne Effect • Examples: Jane Goodall (chimpanzees); Dian Fossey (mountain gorillas) • Cannot draw conclusions about behavior • Cannot generalize to others
Descriptive Methods • Two main types of descriptive methods: • Case Studies • In-depth study of one person/group • Necessary for some types of research: • Child abuse, crime, physical injuries, mental illness, etc. • Examples: Genie, brain injury cases • Cannot generalize to others • Numerous case studies culled together can draw limited conclusions
Inferential methods • Infer conclusions about variables • Stronger than descriptive studies • Main types of inferential methods: • Correlations • Show relationships between variables • Direct (positive) correlation: variables vary together • Inverse (negative) correlation: variables vary separately • CORRELATION DOES NOT MEAN CAUSATION!
Inferential methods • Correlations (continued) • Correlation Coefficients: number indicating the strength and direction of a relationship • Range from -1 to +1 • -1 indicates the strongest inverse relationship • +1 indicates the strongest direct relationship • 0 indicates no relationship
Inferential Methods • Correlations (continued) • How are correlations obtained? • Surveys: essential elements • Representative sample • Obtained through random sampling • Questions/Statements • Multiple Choice • Yes/No • Rank Order • Likert Scale
Inferential Methods • Correlations (continued) • How are correlations obtained? • Longitudinal studies • Same group over long period of time • Cross-Sectional studies • Several cohort groups at the same time
Problems with Interpreting Correlations Directionality: Third Variable:
Inferential Methods • Main types of inferential methods: • Experimentation • Can determine cause & effect relationships • Strongest methodology available • One factor is manipulated • Another factor is measured • Control of all variables is important! • Confounding variables must be controlled!
Inferential Methods • Steps in the experimental process: • Form a hypothesis • Two main types of hypotheses: • Null hypothesis states that no relationship exists between/among the variables • Scientific notation: H0 • Alternative hypothesis states the predicted relationship between/among variables • Scientific notation: HA • Experiments test the null hypothesis, not the alternative
Inferential Methods • Steps in the experimental process: • Create an operational definition of variables in the hypothesis • Written in behavioral terms • Not designed to be “all-inclusive” • Identifies independent and dependent variables
Inferential Methods • Independent & Dependent Variables • DV: the variable that is measured by the researchers • AKA: the “effect” in the study • Easier to identify, because it’s what the researchers are hoping will happen in the study • IV: the variable that is changed/manipulated by the researchers • AKA: the “cause” in the study • It’s what the researchers hope is causing the DV • Must be something researchers can change • Age, gender, IQ, etc., are not IVs – they are “variables of interest”
Inferential Methods • Identify the following IVs & DVs: • Exposing children to public television improves reading skills. • Rewarding comments will make people work harder on an assembly line. • A young monkey will prefer to spend time with a pretend mother monkey covered in cloth who provides no milk over a pretend mother monkey covered in wire who provides milk. • People who have psychotherapy are less likely to have psychological problems in the future. • Being polite to others tends to make people more cooperative. • Extroverted people are more fun at parties.
Inferential Methods • Steps in the experimental process: • Determine the population of participants • Acquire a representative sample from the population by random sampling. • Divide sample into two main groups through random selection: • Experimental group receives the independent variable. • Control group does not receive the independent variable.
Inferential Methods • Steps in the experimental process: • Ways to group participants: • Within-subjects design • AKA: pre/post design • Ps are compared to each other • Is less susceptible to individual differences • Is more susceptible to “practice effects”
Inferential Methods • Steps in the experimental process: • Ways to group participants: • Between-subjects design • Ps are divided into two groups and compared to each other • Is more efficient • Avoids “practice effects” • Is more susceptible to individual differences • Way to address problem: Matched-subjects design • Match Ps according to a predetermined variable (age, gender, IQ, etc.) and make sure each group shares same individual characteristic.
Inferential Methods • Steps in the experimental process: • Ways to control variables: • Placebo-control groups • Blind studies • Single-blind: Ps don’t know which group they are in. • Double-blind: Ps and people conducting the study don’t know which group the Ps are in. • Helps control expectation effects, demand characteristics, and researcher bias • Control environmental conditions
Inferential Methods • Steps in the experimental process: • Conduct the study • Conduct statistical analysis • Descriptive statistics • Measures of central tendency: mode, median, mean, range, standard deviation • Inferential statistics • Determine statistical significance • p = .05 – There is a 95% likelihood that the results of the study are NOT due to chance.
Ethics • Ethics guidelines keep research from harming participants. • Main principles: • The benefits of the study must outweigh the harm to the participants. • Informed consent must be obtained. • Must know they are in a research study • Must be allowed to back out of the study at any time without penalty • Participants must be debriefed about the true intentions of the study afterward.