1. Copyright © Allyn & Bacon 2007 Chapter 2 Research Methods This multimedia product and its contents are protected under copyright law. The following are prohibited by law: Any public performance or display, including transmission of any image over a network; Preparation of any derivative work, including the extraction, in whole or in part, of any images Any rental, lease or lending of the program. ISBN: 0-131-73180-7

2. Copyright © Allyn & Bacon 2007 Why the Scientific Approach? Psychology is different from pseudosciences because it takes the scientific approach to its research. None of the pseudosciences have survived by the scientific method. Psychologists reject approaches that claim to have “evidence” but offer only anecdotes and testimonials.

3. Copyright © Allyn & Bacon 2007 How Do Psychologists Develop New Knowledge? Psychologists, like researchers in all other sciences, use the scientific method to test their ideas empirically

4. Copyright © Allyn & Bacon 2007 Empirical investigation – An approach to research that relies on sensory experience and observation as research data How Do Psychologists Develop New Knowledge? Scientific method – A five-step process for empirical investigation of a hypothesis under conditions designed to control biases and subjective judgments

5. Copyright © Allyn & Bacon 2007 Theory A theory is a testable explanation for a set of facts or observations. Examples are: Einstein’s theory of relativity, germ theory of disease, Darwin’s theory of natural selection, social learning theory Theory doesn’t just simply mean a “hunch” like in everyday language.

6. Copyright © Allyn & Bacon 2007 Emily Rosa and Therapeutic Touch Emily Rosa, a fourth grader, became the youngest published researcher. Her science project challenged TT, a treatment that her mother (a nurse) had explained to her. Emily used the scientific method to examine claims that TT could heal individuals.

7. Copyright © Allyn & Bacon 2007 The Five Steps of the Scientific Method Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Publishing, criticizing, and replicating the results

8. Copyright © Allyn & Bacon 2007 Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Publishing, criticizing, and replicating the results Hypothesis – A statement predicting the outcome of a scientific study Operational definitions – Exact procedures used in establishing experimental conditions and measurement of results The Five Steps of the Scientific Method

9. Copyright © Allyn & Bacon 2007 Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Publishing, criticizing, and replicating the results Independent variable – The variable manipulated by the experimenter Random presentation – Using chance alone to determine the order in which the stimulus is presented The Five Steps of the Scientific Method

10. Copyright © Allyn & Bacon 2007 Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Publishing, criticizing, and replicating the results Data – Information gathered by researcher and used to test a hypothesis Dependent variable – The measured outcome of a study; the responses of participants in a study The Five Steps of the Scientific Method

11. Copyright © Allyn & Bacon 2007 Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Publishing, criticizing, and replicating the results Based on statistical analyses of results, the hypothesis is accepted or rejected The Five Steps of the Scientific Method

12. Copyright © Allyn & Bacon 2007 Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Publishing, criticizing, and replicating the results The Five Steps of the Scientific Method Researchers must find out whether their work can withstand the scrutiny of the scientific community

13. Copyright © Allyn & Bacon 2007 Types of Psychological Research In experiments, the researcher controls all the conditions and directly manipulates the conditions Non-experimental methods include: Correlational studies…relationship between variables Surveys…asking individuals to respond about self Naturalistic observation…collect data unseen Longitudinal studies…group is followed over time Cross-sectional studies…one given time, different ages Cohort-sequential studies…different ages followed brief time Ex-post facto design…there is a condition due to ethics

14. Copyright © Allyn & Bacon 2007 Some terms involved in the experimental method… Basic inquiry Hypothesis Literature Confounding or extraneous variables Controls Subject selection Representative sample Random assignment Double-blind

15. Copyright © Allyn & Bacon 2007 Sources of Bias Sources of bias include: Personal bias…beliefs, preferences, prejudices Expectancy bias…looking for certain outcomes Bias could affect the way an experimenter designs a study, collects data, or interprets results Double blind studies attempt to control bias Researchers must also attempt to control confounding variables

16. Copyright © Allyn & Bacon 2007 Ethics in Research APA: “Ethical Principles of Psychologists and Code of Conduct” Each institution must have IRB Animal research must be approved by IACUC Deception…some is fine but needs debriefing Debriefing…study is explained and it should be made sure that individuals suffer no ill effects Animal research…debate continues

17. Copyright © Allyn & Bacon 2007 Questions Science Cannot Answer The scientific method is not appropriate for answering questions that cannot be put to an objective, empirical test Ethics Morality Religious beliefs Preferences

18. Copyright © Allyn & Bacon 2007 How Do We Make Sense of the Data? Researchers use statistics for two major purposes: (1) descriptively to characterize measurements made on groups or individuals and (2) inferentially to judge whether these measurements are the result of chance

19. Copyright © Allyn & Bacon 2007 Organizing the Data First results must be arranged in a summary chart known as a frequency distribution We can convert the data into a bar graph called a histogram

20. Copyright © Allyn & Bacon 2007 Describing the Data With Descriptive Statistics Descriptive statistics include: The mean (measure of central tendency)—adding all scores and dividing by the number of scores The median (measure of central tendency)—the score that separates the upper half of the scores from the lower half The mode (measure of central tendency)—score that occurs more often than all The range (measure of variability)—difference between highest and lowest values The standard deviation (measure of variability)—average difference between scores and the mean The normal distribution—bell-shaped curve describing the spread of scores…approximately 34% 34% 13% 13% 2% 2%

21. Copyright © Allyn & Bacon 2007 Correlations: A relationship between Two Variables Correlation– A relationship between two variables, in which changes in one variable are reflected in changes in the other variable Correlation coefficient– A number between -1 and +1 expressing the degree of relationship between two variables

22. Copyright © Allyn & Bacon 2007 Making Inferences with inferential statistics Inferential statistics are used to assess whether the results of a study are significant or whether they might be simply the result of chance…this is usually the deciding factor whether or not to reject or accept a hypothesis Statistical significance or difference—the probability that it might be due to chance is less than 5 in a 100…p<.05

23. Copyright © Allyn & Bacon 2007 End of Chapter 2