© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 1 Research Methods In Psychology 2

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 2 Basic Concepts of Research Basis of scientific method –Making observations in systematic way –Follow strict rules of evidence –Critical thinking about evidence Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 3 Empirical Evidence and Operational Definitions Empirical evidence – observations of publicly (confirmable) observable behavior Operational definitions – use operations of measurement to describe observations –Evaluates quality of evidence and allows alternative interpretations Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 4 Theories and Hypotheses Theories – tentative explanations of facts and relationships in science Hypothesis – a prediction based on a theory –Tested to confirm or refute –Can be revised or abandoned Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 5 Representativeness of Samples Sample –Representative of larger group or population of interest –Small group of humans or animals –Unrepresentative sample – misleading or biased test of hypothesis Replication of research removes most doubt Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 6 Research Methods Descriptive studies –Simplest method of scientific inquiry –Describe behavior and mental processes –Most widely used Survey method – ask people’s opinions Naturalistic observation – watch, describe Clinical method – observe in clinic setting –All have advantages and disadvantages Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 7 Research Methods Correlational Studies –Correlational method: measure two variables for statistical relationship –Variable: anything that can be assigned a numerical value –Uses quantitative measures Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 8 Research Methods Correlational Studies –Correlation coefficient Measures each variable Indicates strength ( 0 to  1) and direction (negative or positive) of relationship –Correlation does not mean causation Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 9 Fig. 2.2 Variable 2 21 Variable Hypothetical data illustrating a correlation coefficient of +1.00

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 10 Fig. 2.3 Hypothetical data illustrating a correlation coefficient of Variable 2 21 Variable

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 11 Fig. 2.4 Hypothetical data illustrating a correlation coefficient of zero Variable 2 21 Variable

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 12 Formal Experiments Tests relationship of two or more variables –Allows conclusions about cause-and-effect –Quantitative measures of behavior compared in different conditions created by researchers –Evidence supports or rejects hypothesis Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 13 Formal Experiments Elements –Independent variable – gets manipulated –Dependent variable – amount of change –Experimental group – exposed to independent variable or conditions expected to create change –Control group – presents normal behavior used for comparison –Random assignment – –Experimental control Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide Nonviolent film Violent film Fig. 2.6

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 15 Fig. 2.7 Control group: View nonviolent film Randomly assign into control and experimental groups Full population of interest Experimental group: exposed to independent variable: view violent film

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 16 Formal Experiments Placebo control –Placebo effect: provides no active effect –Use in identical conditions for control and experimental groups Blind experiment –Researchers blind to group membership of participants to rule out experimenter bias Strongest experiments – double blind –Researchers and participants kept blind Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 17 Describing and Interpreting Data Descriptive statistics – summarized data for large groups of participants –Mean: average –Median: midpoint in rank-ordered data –Mode: score appearing most often –Normal distribution: bell-shaped curve –Standard deviation: degree to which scores in ordered distribution are spread out Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide % Giving birth for 1st time Mother’s Age Mode Mean & Median

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 19 Describing and Interpreting Data Reaching conclusions from data –Statistical significance Size of correlation Difference of means are greater than chance –Two issues for significance Larger sample size is better Statistical difference does not equal practical significance Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 20 Ethical Principles of Research Ethics in research with human participants –Freedom from coercion –Informed consent –Limited deception –Adequate debriefing –Confidentiality Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 21 Ethical Principles of Research Ethics of research with nonhuman animals –Necessity –Health –Humane treatment Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 22 Human Diversity: Equal Representation in Research U.S. National Institutes of Health –New applications for research grants involving human subjects must include diverse samples of Both sexes Major racial and cultural groups –Differences may be real and important Research Methods In Psychology

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 23 The End 2 Research Methods In Psychology