Thinking Critically with
Psychology
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Research methods
 Survey
 Case study
– E.g. Stroke victim
 Experimentation
 Naturalistic Observation
– Observing behavior in a singles bar
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Comparing research methods
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How do you get people to study?
 Population
– All NSCC students
 Representative Sample
 Random sample
– Ensures a representative sample
 Random assignment
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Generalizing (Problems)
 Generalizing from unrepresentative samples
 Generalizing from select cases
– Most remedial reading students in Mrs.
Brown’s class are boys
– Therefore, boys have more trouble reading than
girls
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Random sampling
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What do you study? - Variables
 Variables
 Independent variable
 Dependent variable
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How are variables related? Correlation
 Positive and negative
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Positive correlation
 Mortality rates increase as people age
 Grades increase as study time increase
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Negative correlation
 As income increases free time decreases
 As one goes up, the other goes down
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No Correlation
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Confusing correlation with
causation
 “Correlation is not causation”
 Large brains (or ice cream) & violence
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Illusory correlation
 Buying stocks that performed well last year
 Adoption and conception
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Hindsight bias
 Explaining events in hindsight
– Lee Harvey Oswald & Pres. Kennedy
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Perceiving order in random
events
 Both have an equal chance of happening
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Perceiving order in random
events (Cont.)
 Twins separated at birth having similar
interests, jobs, etc.
 Similarities between Lincoln and Kennedy.
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The experiment
 Control Condition
 Placebo effect
– Placebo = Pill with no drug
 The double blind procedure
– Neither experimenter nor subject knows which
pill is the drug or placebo.
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