Thinking Critically with Psychological Science Research & Statistics Chapter 1
Thinking Critically with Psychological Science
Research & Statistics
Chapter 1
Critical Thinking
thinking that does not blindly accept arguments and conclusions
Examines discernsevaluates
AssumptionsHidden Valuesevidence
Limits of Intuition and Common Sense
Hindsight Bias
Overconfidence
But first…
A brief example of how NOT to conduct an experiment care of Dr. Venkman
Research Strategies
Theory
Hypothesis
The Scientific Method
generate or refine
research and observations
lead to
hypothesis
theories
Operational Definition
Example-IQ TESTS
Replication
Case Study
Survey
False Consensus Effect
Population
Random Sample
Research StrategiesIf marbles of two
colors are mixed well in the large jar, the fastest way to know their ratio is to blindly transfer a few into a smaller one and count them
Naturalistic Observation
observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation
Correlation Coefficient
a statistical measure of the extent to which two factors vary together and thus how well either factor predicts the other
Correlation coefficient
Indicates directionof relationship
(positive or negative)
Indicates strengthof relationship(0.00 to 1.00)
r = +.37
Scatterplot
–a graphed cluster of dots, each of which represents the values of two variables–the slope of the points suggests the direction of the relationship–the amount of scatter suggests the strength of the correlation–little scatter indicates high correlation–also called a scattergram or scatter diagram
scatterplots
Perfect positivecorrelation (+1.00)
No relationship (0.00) Perfect negativecorrelation (-1.00)
Scatterplot of Height and Temperament55 60 65 70 75 80 85
959085807570656055504540353025
Temperamentscores
Height in inches
Research StrategiesHeight and Temperament of 20 Men
12345678910
11121314151617181920
80636179746962757760
64767166737063716870
75666090604242608139
48697257637530578439
SubjectHeight in
Inches Temperament SubjectHeight in
Inches Temperament
Research Strategies
(1)Low self-esteem Depression
(2)Depression Low self-esteem
Low self-esteem
Depression
(3)Distressing events
or biologicalpredisposition
could cause
could cause
could cause
or
or
and
Illusory Correlation
Illusory Correlationthe perception of a relationship where none exists
Conceive Do not conceive
Adopt
Do notadopt
disconfirming evidence
confirming evidence
disconfirming evidence
confirming evidence
Random Sequences
Your chances of being dealt either of these hands is precisely the same: 1 in 2,598,960.
the investigator manipulates one or more factors (independent variables) to observe their effect on some behavior or mental process (the dependent variable) while controlling other relevant factors by random assignment of subjects
Experiment
Experiment cont.
by random assignment of participants the experiment controls other relevant factors
Double-blind Procedure
Placebo
Experimental Condition
Control Condition
Random Assignment
**minimizes pre-existing differences between those assigned to the different groups
Independent Variable **the variable whose effect is
being studied
Dependent Variable …in psychology it is usually a
behavior or mental process
Statistical Reasoning
Mode
Mean
Median
Statistical ReasoningA Skewed Distribution
15 20 25 30 35 40 45 50 90 475 71070
Mode Median Mean
One Family Income per family in thousands of dollars
Statistical ReasoningRange
Standard Deviation
Statistical Significance
Positive Skew
Negative Skew
polygon
HISTOGRAM