1. Copyright © Allyn & Bacon 2007
Research Methods
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2. How Do Psychologists Develop New Knowledge?
Psychologists, like researchers in all other sciences, use the scientific method to test their ideas empirically
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3. How Do Psychologists Develop New Knowledge?
Empirical investigation – An approach to research that relies on sensory experience and observation as research data
Scientific method – A five-step process for empirical investigation of a hypothesis under conditions designed to control biases and subjective judgments
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4. 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
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5. The Five Steps of the Scientific Method
Developing a hypothesis
Hypothesis – A statement predicting the outcome of a scientific study
Performing a controlled test
Gathering objective data
Operational definitions – Exact procedures used in establishing experimental conditions and measurement of results
Analyzing the results
Publishing, criticizing, and replicating the results
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6. The Five Steps of the Scientific Method
Developing a hypothesis
Independent variable – The variable manipulated by the experimenter
Performing a controlled test
Gathering objective data
Random presentation –
Using chance alone to determine the order in which the stimulus is presented
Analyzing the results
Publishing, criticizing, and replicating the results
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7. The Five Steps of the Scientific Method
Developing a hypothesis
Performing a controlled test
Data – Information gathered by researcher and used to test a hypothesis
Gathering objective data
Analyzing the results
Dependent variable – The measured outcome of a study; the responses of participants in a study
Publishing, criticizing, and replicating the results
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8. The Five Steps of the Scientific Method
Developing a hypothesis
Performing a controlled test
Gathering objective data
Based on statistical analyses of results, the hypothesis is accepted or rejected
Analyzing the results
Publishing, criticizing, and replicating the results
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9. The Five Steps of the Scientific Method
Developing a hypothesis
Performing a controlled test
Gathering objective data
Analyzing the results
Researchers must find out whether their work can withstand the scrutiny of the scientific community
Publishing, criticizing, and replicating the results
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10. 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
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11. 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
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12. Copyright © Allyn & Bacon 2007
Ethics in Research
Deception
Debriefing
Animal research
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13. 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
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14. 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
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15. Copyright © Allyn & Bacon 2007
Class Survey
Write down whether you agree or disagree with the following statements
There is too much concern in the courts for the rights of criminals
The death penalty should be abolished
Wealthy people should pay a larger share of taxes then they do now
Federal military spending should be increased
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16. 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
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17. Describing the Data With Descriptive Statistics
Descriptive statistics include:
The mean
The median
The mode
The range
The standard deviation
The normal distribution
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18. 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
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19. 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
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