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:

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

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

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

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

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

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

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

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

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 Surveys Naturalistic observation Longitudinal studies Cross-sectional studies Cohort-sequential studies

Copyright © Allyn & Bacon 2007 Sources of Bias Sources of bias include: Personal bias Expectancy bias 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

Copyright © Allyn & Bacon 2007 Ethics in Research Deception Debriefing Animal research

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

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

Copyright © Allyn & Bacon 2007 Class Survey Write down whether you agree or disagree with the following statements 1.There is too much concern in the courts for the rights of criminals 2.The death penalty should be abolished 3.Wealthy people should pay a larger share of taxes then they do now 4.Federal military spending should be increased

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

Copyright © Allyn & Bacon 2007 Describing the Data With Descriptive Statistics Descriptive statistics include: The mean The median The mode The range The standard deviation The normal distribution

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

Copyright © Allyn & Bacon 2007 Making Inferences with inferential statistics Inferential statistics are used to assess whether the results of a study are reliable or whether they might be simply the result of chance Sampling Random sample Representative sample Statistical significance

Copyright © Allyn & Bacon 2007 End of Chapter 2