Transcript Chapter Two Research Methods

Chapter Two
Research
Methods
This multimedia product and its contents are protected under copyright law. The following are prohibited by law:
•Any public performance or display, including transmission of any image over a network;
•Preparation of any derivative work, including the extraction, in whole or in part, of any images
Copyright © Allyn & Bacon 2007
•Any rental, lease or lending of the program.
• ISBN: 0-131-73180-7
How Do
Psychologists
Develop New
Knowledge?
Copyright © Allyn & Bacon 2007
Operational Definitions
Exact procedures
used in establishing
conditions and the
measurement of
results in an
experiment.
Defining the Operation
Copyright © Allyn & Bacon 2007
The Five Steps of the Scientific Method
Developing a
hypothesis
Performing a
controlled test
Independent Variable
The stimuli you are studying
Gathering
objective data
Analyzing the
results
Publishing,
criticizing, and
replicating the
results
A condition that the experimenter
changes independently of all the
other carefully controlled
conditions.
Copyright © Allyn & Bacon 2007
Independent Variable v. Dependent Variable
Independent Variable
Dependent Variable
The measured outcome
of a study
The stimuli you are
As in….
studying
The responses made by
the participants in
For example………
experiment.
--In a study of how different dosages ofyour
a drug
are related to
• the severity of the
the severity of symptoms of a disease,
symptoms of the disease is a dependent variable.
--The administration of the drug in specified doses is the
independent variable.
Copyright © Allyn & Bacon 2007
The Independent Variable here
is…
The Amount of Light
The Dependent Variable here
is.…
How much the plants
Copyright © Allyn & Bacon 2007
Confounding Variables
• An unwanted variable that can have
unpredictable influence over the results of a
study.
– EX: Seniors are more likely to have tried
drugs than freshman.
• Confounding or extraneous variables
might included socio-economical
differences in the 2 classes, cohort
differences, educational offerings may
differ and influence personal choices,
etc…
Bias in Research
Types of Bias
• Personal Bias
• Expectancy Bias
Method to avoid Bias
• Double-blind studies: Neither the researcher,
nor the subject knows if they are in the control
or the experimental group (used often to test
new meds)
• Identifying confounding/extraneous factors also
help to minimize incorrect research results
Ethics
• American Psychological Association (APA)
– Ethical Principles of Psychologists and Code of
Conduct
• Institutional Review Board (IRB)
– Reviews all research conducted by an institution,
university, etc
• Institutional Animal Care and Use Committee
(IACUC)
– Must approve all animal research
• Uses the ABC’s of animal research as a guideline:
Appropriate, Beneficial, Caring
Ways to Conduct a NonExperimental Study
• Correlational Study
– Occurs ex post facto
– Correlated does NOT mean causal
– +/-correlation coefficients show relationships between 2
variables on a scale of –1.0-+1.0
• Survey
• Naturalistic Observation (Concealed, Open, and NonParticipant)
Long Range Studies
• Longitudinal Study
• Cross-Sectional Study
• Cohort-Sequential Study
Correlation
• A relationship between 2 variables
–+ as one variable increases, the other
increases; OR as one variable
decreases, the other decreases
• The more McD’s you eat, the more
you will weigh
–- as one variable increases, the other
decreases
• The more cigarettes you smoke, the
lower your running endurance
Correlation Coefficient
• A number between –1.0 and +1.0, which
shows the extent of the variables’
relationship
–A score of 0 would indicate NO
relationship
–Whether positive or negative, the closer
to 1, the stronger the relationship
• The more clustered the data points in
a graph, the stronger the relationship
Inferential Statistics
• Used to infer whether or not 2
groups are similar or different
–Hypothesis: Students who listen
to music while studying are more
academically successful. We see
if listening to music correlate to
high achieving and low achieving
groups of students
Sampling
• Random- drawn from a hat
• Representative- Gallup pollsEX: Are you 18-25? Do you
see yourself as a Democrat or
Republican?
Statistical Significance
• We study Psychology in probabilities and likelihoods,
NOT absolutes (it’s a SOFT science)
• We use p<.05 (5%) to determine significant difference
between 2 groups: probability results are due to
chance is less than 5 %
– MEANING: IF we looked at 2 groups from the earlier
hypothesis and find that 92% of high achieving students
listen to music while studying, whereas 12% of low achieving
students listen to music, we can INFER that listening to
music increases achievement.
• If the numbers were 92% listen in both groups, we can
INFER that studying to music will not make a difference in
achievement.
• If we find 92% in the hi ach. Group listen to music, and
the low group just doesn’t study, NO inference can be