The Scientific Approach in Psychology: Seeking Laws and Exploring Relationships

1. Chapter 2: The Research Enterprise in Psychology

2. The Scientific Approach:A Search for Laws • Basic assumption: events are governed by some lawful order • Goals: • Measurement and description • Understanding and prediction • Application and control

3. Figure 2.2 Flowchart of steps in a scientific investigation

4. The Scientific Method: Terminology • Operational definitions are used to clarify precisely what is meant by each variable • Participants or subjects are the organisms whose behavior is systematically observed in a study • Data collection techniques allow for empirical observation and measurement • Statistics are used to analyze data and decide whether hypotheses were supported

5. Table 2.1 Key Data Collection Techniques in Psychology

6. The Scientific Method: Terminology • Findings are shared through reports at scientific meetings and in scientific journals – periodicals that publish technical and scholarly material • Advantages of the scientific method: Clarity of communication and relative intolerance of error • Research methods: General strategies for conducting scientific studies

7. Peer Review of Scientific Articles • The process of publishing scientific studies allows other experts to evaluate and critique new research findings. • They carefully evaluate each study’s methods, statistical analyses, and conclusions, as well as its contribution to knowledge and theory. • The purpose of the peer review process is to ensure that journals publish reliable findings based on high-quality research.

8. Experimental Research: Looking for Causes • Experiment = manipulation of one variable under controlled conditions so that resulting changes in another variable can be observed • Detection of cause-and-effect relationships • Independent variable (IV) = variable manipulated • Dependent variable (DV) = variable affected by manipulation • How does X affect Y? • X = Independent Variable, and Y = Dependent Variable

9. Experimental and Control Groups:The Logic of the Scientific Method • Experimental group • Control group • Random assignment • Manipulate independent variable for one group only • Resulting differences in the two groups must be due to the independent variable • Extraneous and confounding variables

10. Figure 2.6 The basic elements of an experiment

11. Advantages and Disadvantages of Experimental Research • Strengths: • conclusions about cause-and-effect can be drawn • Weaknesses: • artificial nature of experiments • ethical and practical issues

12. Descriptive/Correlational Methods:Looking for Relationships • Methods used when a researcher cannot manipulate the variables under study • Naturalistic observation • Case studies • Surveys • Allow researchers to describe patterns of behavior and discover links or associations between variables but cannot imply causation

13. Statistics and Research:Drawing Conclusions • Statistics – using mathematics to organize, summarize, and interpret numerical data • Descriptive statistics: organizing and summarizing data • Inferential statistics: interpreting data and drawing conclusions

14. Descriptive Statistics:Measures of Central Tendency • Measures of central tendency = typical or average score in a distribution • Mean: arithmetic average of scores • Median: score falling in the exact center • Mode: most frequently occurring score • Which most accurately depicts the typical?

15. Figure 2.11 Measures of central tendency

16. Descriptive Statistics: Correlation • When two variables are related to each other, they are correlated. • Correlation = numerical index of degree of relationship • Correlation expressed as a number between 0 and 1 • Can be positive or negative • Numbers closer to 1 (+ or -) indicate stronger relationship

17. Figure 2.13 Positive and negative correlation

18. Figure 2.14 Interpreting correlation coefficients

19. Correlation:Prediction, Not Causation • Higher correlation coefficients = increased ability to predict one variable based on the other • SAT/ACT scores moderately correlated with first year college GPA • 2 variables may be highly correlated, but not causally related • Foot size and vocabulary positively correlated • Do larger feet cause larger vocabularies? • The third variable problem

20. Inferential Statistics:Interpreting Data/Drawing Conclusions • Hypothesis testing: do observed findings support the hypotheses? • Are findings real or due to chance? • Statistical significance = when the probability that the observed findings are due to chance is very low • Very low = less than 5 chances in 100/ .05 level

21. Evaluating Research:Methodological Pitfalls • Sampling bias • Placebo effects • Distortions in self-report data: • Social desirability bias • Response set • Experimenter bias • the double-blind solution

22. Ethics in Psychological Research:Do the Ends Justify the Means? • The question of deception • The question of animal research • Controversy among psychologists and the public • Ethical standards for research: the American Psychological Association • Ensures both human and animal subjects are treated with dignity

23. Figure 2.17 Ethics in research

24. The Internet and Psychological Research • Internet-mediated research refers to studies in which data collection occurs over the web. • Possible Advantages • Samples that are much larger and much more diverse than the samples typically used in laboratory research • Have the potential to yield more diverse and representative samples

25. The Internet and Psychological Research • Potential Disadvantages • Sampling bias resulting from self-selection may be a more troublesome issue in Internet-mediated research • Web users tend to be younger, brighter, and more affluent than nonusers • Data are collected under far less controlled conditions than in traditional studies