Transcript Unit 2: Research Methods

Unit 2: Research Methods
Module 4: The Need for Psychological Science
Module 5: The Scientific Method and Description
Module 6: Correlation and Experimentation
Module 7: Statistical Reasoning in Everyday Life
Module 8: FAQ’s about Psychology
Did We Know It All Along?
Hindsight Bias:
• the tendency to believe,
after learning an
outcome, that one would
have foreseen it.
• Also known as the “I
knew it all along”
phenomenon.
Overconfidence
• We tend to think we know more than
we do
– Richard Goranson Study (1978)
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ETRYN------------ ENTRY
GRABE------------ BARGE
OCHSA
Perceiving Order in Random Events
• Comes from our need to make sense
out of the world
– Coin flip
– Poker hand
– Your test/quiz answers
“An event that happens to but 1 in 1 billion people
everyday occurs 7 times a day, 2,500 times a year”
The Scientific Attitude: Curious, Skeptical
and Humble
• Three main components
– Curious eagerness
– Skeptical but not cynical, open but not gullible
– Open-minded humility before nature
• Key Point: Hindsight bias, overconfidence
and our tendency to perceive patters in
random events often lead us to overestimate
our intuition.
The Scientific Method
• Theory
• an explanation using an integrated set of
principles that organizes observations and
predicts behaviors or events.
• Hypothesis
•
•
a testable prediction, often implied by a
theory.
Can be confirmed or refuted
The Scientific Method
• Operational Definitions:
• In order to do research on subjective concepts
(i.e., love, fear, anxiety) researchers must make
these subjective concepts objective.
• They must be observable and measurable.
• Operational definition of Anger for a road rage
study:
– Anger will be defined as presence of 3 of the following:
 Increase in heart rate
 Emotional Outbursts
 Flushing of the face
 Self report of anger (likert scale)
 Physical Confrontation
The Scientific Method
• Replication
– repeating the essence of a research study, usually
with different participants in different situations, to see
whether the basic finding extends to other participants
and circumstances
– Must have clear operational definition to replicate
a study
The Scientific Method
Description
• Case Study
•
an descriptive technique in
which one individual or group is
studied in depth in the hope of
revealing universal principles
•
Pros?
•
Cons?
Description
• Naturalistic Observation
– Describes behavior
– Does not explain behavior
– Pros? Cons?
Description
• Survey
– Looks at many cases at once
– Anonymous
• What percent of people pee in the shower?
• Word effects
• Random sampling
– Representative sample
– Sampling bias
Just for fun… 
Correlation
• When two variables are related to each other,
they are correlated.
• Correlation = numerical index of degree of
relationship
– Correlation expressed as a number between 0 and
1
– Can be positive or negative
– Numbers closer to 1 (+ or -) indicate stronger
relationship
Correlation
• Higher correlation coefficients = increased
ability to predict one variable based on the
other
– SAT/ACT scores moderately correlated with first
year college GPA
• 2 variables may be highly correlated, but not
causally related
– Foot size and vocabulary positively correlated
– Do larger feet cause larger vocabularies?
– The third variable problem
Correlation
• Illusory Correlation
– Perceived but non-existent correlation
– A random coincidence
Experimental Design
• Experiment = manipulation of one variable
under controlled conditions so that resulting
changes in another variable can be observed
– Detection of cause-and-effect relationships
• Independent variable (IV) = variable
manipulated
• The Cause
• Dependent variable (DV) = variable affected
by manipulation
• The Effect
Experimental Design
• Experimental group
– Gets the IV
• Control group
– Does not get the IV
• Random assignment
– Necessary to minimize extraneous variables
• Extraneous and confounding variables
– Might alter the accuracy of results
• Participants are sleepy, in a bad mood, sick, etc.
Resulting differences in the two groups must be due to the
independent variable
Methodological Pitfalls
• Sampling bias
– Not using a diverse group of your population
• Placebo effects
• Distortions in self-report data:
– Social desirability bias
• Saying whatever you think the researcher wants you to say
– Response set
• Tendency to always mark the same answer
• Experimenter bias
– the double-blind solution
Descriptive Stats: Histogram
Descriptive Stats: Measures of Central
Tendency
• Mean (arithmetic average)
• Median (middle score)
• Mode (occurs the most)
Normal Bell Curve
Inferential Statistics:
Statistical Significance
• Statistical significance = when the
probability that the observed findings are
due to chance is very low
– Very low = less than 5 chances in 100/ .05
level
– Represented by a “p”
– Ex: p=.02 would mean that there was a 2 in
100 chance that the results were due to
chance.
Ethics in Research
• The question of deception
• The question of animal research
– Controversy among psychologists and the
public
• Ethical standards for research: the
American Psychological Association
– Ensures both human and animal subjects are
treated with dignity