PSYCHOLOGY
Chapter 2 Notes
Psychological Research Methods and Statistics
WHAT IS RESEARCH?
•
Psychologists must first decide how to approach the research issue. Then they conduct
the research in one of a variety of ways to test a hypothesis, solve a problem, or confirm
previous findings
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Pre-Research Decisions
• Begin by developing a hypothesis
• Look for evidence/conduct research
• Researchers select a sample – a relatively small group out of the total population
under study
• Must be representative of the population
• Choose a purely random sample
• Use a stratified sample – subgroups in the population are represented
proportionally
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Methods o f Research
• Naturalistic Observation – observing behaviors with out intruding or disturbing those
being observed
• Case studies are intensive studies of a person or group of people
• Long-term observations
• Diaries
• Tests
• Interviews
• Surveys involve interviews and/or questionnaires. Very practical way to gather data
• Longitudinal Studies occur when a psychologist studies the same group of people at
regular intervals over a period of years to determine whether their behavior and/or
feelings have changed and if so, how.
• Cross-Sectional Studies are when psychologist organize people into groups on the
basis of age
• The groups are randomly sampled with simultaneously with
• Surveys
• Tests
• Observations
• Correlations and explanations
• Correlations describe how two sets of data relate to each other
• Experiments
• Hypothesis – educated guess
• Variables – conditions and behaviors that are subject to change
• Independent variable is changed or altered so the experimenters can
observe its effects
• Dependent variable changes in relation to the independent variable
• Experimental group – those who are exposed to the independent variable
• Control group – those who are not exposed to the independent variable
• Ethical Issues
• Ethics are the methods of conduct or standard for proper and responsible
behavior
• Plan to minimize possible misleading results
• Maintain the dignity and welfare of the participants
• Obey all state, federal, and professional laws, regulations, and standards
• Reach agreements regarding the rights and responsibilities of the
participants and the researchers
• Obtain signed, informed consent
• Deception is used only if no better alternative is available
PROBLEMS AND SOLUTIONS IN RESEARCH
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The investigation of psychological issues is a painstaking process. Psychologists must
recognize and resolve errors while doing research
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Self-fulfilling Prophecy
• Self-fulfilling Prophecy involves having expectations about a behavior and then
acting in some way, usually unknowingly to carry out that behavior
• Avoiding a Self-fulfilling Prophecy
• Double-blind experiment – neither the experimenter nor the participants know
which participants are receiving the experimental stuff
• Single-blind experiment – the participants don’t know if they’ve received the
stuff or the placebo, but the experimenter does.
•
The Milgram Experiment
• Stanley Milgram (1960s)
• Told people to act like they were receiving electric shocks to see how the person
supposedly delivering the shocks would respond
• Most of those delivering the shocks continued to deliver them through the
maximum capacity of electricity
• Conclusion was the people will hurt others when told to do so by an
authority figure
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Placebo Effect
• Placebo effect happens when a person’s illness or physical state changes when they
simply think they are receiving treatment
STATISTICAL EVALUATION
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Psychologists must collect and evaluate evidence to support their hypothesis.
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Descriptive Statistics
• Descriptive Statistics is the listing and summarizing of data in a practical, efficient
way through graphs and averages
• Frequency distributions are common
• Frequency polygons are like line graphs that compare two sets of data
• Normal Curve (aka a bell curve) is where the curve is highest in the middle and
tapers off towards both ends. It is symmetrical
• Measures of Central Tendency
• Central tendency is a number that describes something about the “average”
score
• Mode is the most frequent score
• Bimodal indicates there are two frequent scores/modes
• Mean is what most people think of as an average
• This is the balance point
• Measures of Variance
• Measures of variance provide an index of how spread out the scores of a
distribution are
• Standard Deviation is a better measure of variance because it uses all the data
points in its calculation.
• Correlation Coefficients describe the direction and strength of the relationship
between two sets of observations
• Positive correlation means as one variable increases so does the other
• Negative correlation means as one variable increases, the other decreases
• Scatterplots are graphs of scores on the two variables
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Inferential Statistics
• Inferential statistics allow researchers to determine whether the data they collect
support their hypotheses, or whether their results are merely due to chance
outcomes
• Probability - what is the probability that something will happen?
• Chance – could the results be due to chance?