Using The Scientific method in Psychology

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1 CHAPTER FIVE Using The Scientific method in Psychology 1 The Scientific Method in Psychology Science The key elements of the scientific approach are: Objective measurements of the phenomenon under consideration The ability to verify or confirm the measurements made by other individuals (Replication) Self-correction of errors and faulty reasoning Exercising control to rule out the influence of unwanted factors 2 Components of the Scientific Method Objectivity A good researcher strives to be as objective as possible. Psychologists select research participants in such a manner as to avoid biasing factors (such as age or sex). Researchers frequently make their measurements with instruments in order to be as objective as possible. We describe such measurements as being empirical because they are based on objectively quantifiable observations. 3 1

2 Components of the Scientific Method Confirmation of Findings Because the procedures and measurements are objective, we should be able to repeat them and confirm the original results. Confirmation of findings is important for establishing the validity of research. Psychologists use the term replication to refer to a research study that is conducted in exactly the same manner as a previous study. A replication with extension generates new information at the same time it confirms previous findings. 4 Components of the Scientific Method Self-correction Errors and faulty reasoning that become apparent should lead to a change in the conclusions we reach. If experimental evidence fails to support the predicted relations between our independent and dependent variables, we change our view about how nature operates. 5 Components of the Scientific Method Control Direct manipulation of factors of major interest. An experiment is an implementation of control by manipulating the factor(s) that is the central focus of research. Control of unwanted factors Potentially influential and undesirable factors (other than the factor of major interest) are not allowed to change. 6 2

3 The Psychological Experiment Experiment An attempt to determine the cause-and-effect relations that exist in nature. Researchers are interested in determining those factors that result in or cause predictable events. In its most basic form the psychological experiment consists of three related factors: The independent variable The dependent variable Extraneous variables 7 The Psychological Experiment Independent Variable (IV) The factor that is the major focus of the research and that the researcher directly manipulates. Manipulation of the IV corresponds to one use of the term control. 8 The Psychological Experiment The IV is: Independent Can be directly manipulated by the investigator. Variable Is able to assume two or more values (levels). E.g., comparing 3 different types of diets. The causal part of the relation we seek to establish. 9 3

The Psychological Experiment Dependent Variable (DV) Consists of the recorded information or results of the experiment. Is the effect half of the cause-and-effect relation we are examining.

4 The Psychological Experiment Dependent Variable (DV) Consists of the recorded information or results of the experiment. Is the effect half of the cause-and-effect relation we are examining. Changes in DV scores will depend on the manipulation of the IV. 10 The Psychological Experiment Extraneous Variables Are there factors, other than the independent variable, that can influence the dependent variable and change the results of your experiment? When an extraneous variable is present, we have no way of knowing whether the extraneous variable or the IV caused the effect we observe. Attention to extraneous variables represents another use of the term control. 11 Establishing Cause-and- Effect Relations Only when we manipulate an independent variable and control potential extraneous variables are we able to infer a cause-andeffect relation. 12 4

5 Examples Researchers were interested in examining whether writing or drawing about past emotional experiences would relieve anxiety. Female college students either wrote about emotional topics, drew about emotional topics, or wrote about non-emotional topics daily for 3-5 days. Anxiety and stress were measured using standard questionnaires (Ittayem & Cooley, 2004). (a) Independent Variable (IV): (b) Levels of the IV: (c) Dependent Variable (DV): (d) Extraneous Variable: 13 Copyright 2010 Pearson Education, Inc., Upper Saddle River, NJ All rights reserved. Examples 14 Patients at a health clinic received either their usual care or health care targeting the patients particular stages of change. Researchers measured the extent of positive change for various health behaviors (fat intake, exercise, smoking; Ellington & Martz, 2002). (a) Independent Variable (IV): (b) Levels of the IV: (c) Dependent Variable (DV): (d) Extraneous Variable: Copyright 2010 Pearson Education, Inc., Upper Saddle River, NJ All rights reserved. More examples Examples from research projects 15 Copyright 2010 Pearson Education, Inc., Upper Saddle River, NJ All rights reserved. 5

6 Formulating the Research Hypothesis A research hypothesis is simply a formal statement of your research question, taking into account what you learned from searching the literature. The research or experimental hypothesis is our prediction about the relation that exists between the independent variable that we are going to manipulate and the dependent variable that we will record. 16 Characteristics of the Research Hypothesis Types of Statements Synthetic Statements Are those statements that can be either true of false (e.g. Abused children have lower self-esteem ). Analytic Statements Are those statements that are always true (e.g. I am making an A or I am not making an A ). Contradictory Statements Are those statements that are always false (e.g. I am making an A and I am not making an A ). 17 Characteristics of the Research Hypothesis General Implication Form you must be able to state (or restate) the research hypothesis in general implication ( if then ) form. The if portion of such statements refers to the independent variable manipulation(s) that we are going to make, whereas the then portion of the statement refers to the dependent variable changes we expect to observe. Principle of falsifiability When an experimental hypothesis is stated in general implication form, it is possible that a result is true (supported by the results of the study) or false (not supported by the results of the study). 18 6

Characteristics of the Research Hypothesis Types of Reasoning Inductive Logic Involves reasoning from specific cases to general principles.

7 Characteristics of the Research Hypothesis Types of Reasoning Inductive Logic Involves reasoning from specific cases to general principles. Inductive logic is the process that is involved in the construction of theories. Deductive Logic Involves reasoning from general principles to specific conclusions or predictions. Source: Wann, D. L. & Dolan, T. J. (1994). Spectator s evaluations of rival and fellow fans. The Psychological Record, 44, Characteristics of the Research Hypothesis Directional versus Nondirectional Research Hypotheses Directional Hypotheses Specify the directional outcome of the experiment. Nondirectional Hypotheses Do not predict the exact outcome of an experiment, but only that the groups we are testing will differ. 20 Characteristics of the Research Hypothesis Directional versus Nondirectional Research Hypotheses Which type of hypothesis should you choose? If the theory you are testing calls for it, and you are relatively certain of your prediction, a directional hypothesis increases the chances of finding a statistically significant result. A more conservative approach using a nondirectional hypothesis may make it slightly more difficult to achieve statistical significance, but presents less potential for disappointment with the outcome of a research project. 21 7

8 Characteristics of the Research Hypothesis A New View of Hypothesis Testing Proctor and Capaldi (2001) contend that hypothesis testing is not a simple affair; the importance of the research problem or promise of the research program may dictate whether researcher will stay with a problem even if hypotheses initially disconfirmed. Hypothesis testing involving a theory can be harmful if done too soon in its development when relevant variables not known and it may be easy to disconfirm a hypothesis. Argue that researchers never able to obtain a clear-cut test of a hypothesis anyway. Suggest that researchers use more inductive logic when a theory is new and let the data be their guide. 22 8

Chapter 2. The Research Process: Coming to Terms Pearson Prentice Hall, Salkind. 1

Chapter 2. The Research Process: Coming to Terms Pearson Prentice Hall, Salkind. 1 Chapter 2 The Research Process: Coming to Terms 2009 Pearson Prentice Hall, Salkind. 1 CHAPTER OBJECTIVES - STUDENTS SHOULD BE ABLE TO: Describe the research process from formulating questions to seeking