Chapter 2 The Scientific Method
CHAPTER OUTLINE AND OBJECTIVES
I. Scientific and Everyday Approaches to Knowledge
· The scientific method is empirical and requires systematic, controlled observation.
· Scientists gain the greatest control when they conduct an experiment; in an experiment, researchers manipulate independent variables to determine their effect on behavior.
· Dependent variables are measures of behavior used to assess the effects of independent variables.
· Scientific reporting is unbiased and objective; clear communication of constructs occurs when operational definitions are used.
· Scientific instruments are accurate and precise; physical and psychological measurement should be valid and reliable.
· A hypothesis is a tentative explanation for a phenomenon; testable hypotheses have clearly defined concepts (operational definitions), are not circular, and refer to concepts that can be observed.
A. General Approach
II. Goals of the Scientific MethodThe scientific method is intended to meet four goals: description, prediction, explanation, and application.
· Psychologists seek to describe events and relationships between variables; most often, researchers use the nomothetic approach and quantitative analysis.
· Correlational relationships allow psychologists to predict behavior or events, but do not allow psychologists to infer what causes these relationships.
· Psychologists understand the cause of a phenomenon when the three conditions for causal inference are met: covariation, time-order relationship, and elimination of plausible alternative causes.
· The experimental method, in which researchers manipulate independent variables to determine their effect on dependent variables, establishes time order and allows a clearer determination of covariation.
· Plausible alternative causes for a relationship are eliminated if there are no confoundings in a study.
· Researchers seek to generalize a study’s findings to describe different populations, settings, and conditions.
· In applied research, psychologists apply their knowledge and research methods to improve people’s lives.
· Psychologists conduct basic research to gain knowledge about behavior and mental processes and to test theories.
III. Scientific Theory Construction and Testing
· Theories are proposed explanations for the causes of phenomena, and they vary in scope and level of explanation.
· A scientific theory is a logically organized set of propositions that defines events, describes relationships among events, and explains the occurrence of events.
· Intervening variables are concepts used in theories to explain why independent and dependent variables are related.
· Successful scientific theories organize empirical knowledge, guide research by offering testable hypotheses, and survive rigorous testing.
· Researchers evaluate theories by judging the theory’s internal consistency, observing whether hypothesized outcomes occur when the theory is tested, and noting whether the theory makes precise predictions based on parsimonious explanations.
Review the questions appear in the textbook at the end of Chapter 2.
These review questions appear in the textbook (without answers) at the end of Chapter 2, and can be used for a homework assignment or exam preparation. Answers to these questions appear in italic.
1. For each of the following characteristics, distinguish between the scientific approach and everyday approaches to knowledge: general approach, observation, reporting, concepts, instruments, measurement, and hypotheses.
Refer to Table 2.1, the scientific approach differs from nonscientific (everyday) approaches to knowledge (p.28). For each
characteristic a description of the scientific approach appears first followed by a description of the nonscientific approach.
2. Differentiate between an independent variable and a dependent variable, and provide an example of each that could be used in an experiment.
Read (p.32 -33)
3. What is the major advantage of using operational definitions in psychology? In what two ways has the use of operational definitions been criticized
Read (pp. 36–37)
4. Distinguish between the accuracy and the precision of a measuring instrument.
Read (p. 37)
5. What is the difference between the validity of a measure and the reliability of a measure?
Read (p. 39)
6. Identify the four goals of the scientific method and briefly describe what each goal is intended to accomplish.
Read (pp. 41, 45, 47, 49)