RESEARCH METHODS
CHAPTER 2
PSYCHOLOGY’S
SCIENTIFIC METHOD
4 GOALS OF PSYCHOLOGY
1)
2)
3)
4)
Describe behavior
Predict behavior
Explain behavior
Control behavior
5 STEPS OF THE SCIENTIFIC METHOD
1. Observing some Phenomenon
2. Formulating Hypotheses and Predictions
3. Testing through Empirical Research
4. Drawing Conclusions
5. Evaluating the Theory
5 STEPS OF THE SCIENTIFIC METHOD
1. Observing some Phenomenon
• Asking questions
• Variables
2. Formulating Hypotheses and Predictions
5 STEPS OF THE SCIENTIFIC METHOD
3. Testing through Empirical Research: Choose your research method
Descriptive Research: describes some phenomenon
• Naturalistic Observation
• Survey/ Interview
• Psychological/ Physiological Tests
• Case Study
• Archival Research
Correlational Research: shows relationships
Experimental Research: shows cause and effect
5 STEPS OF THE SCIENTIFIC METHOD
3. Testing through Empirical Research: Choose your research design
(NOT for Experimental Research)
Cross-sectional: Study participants of different age groups at the
same time.
• Advantage: quicker, less costly
• Disadvantage: cohort effects, sample variability
Longitudinal: Study a particular group of participants over a
prolonged period of time.
• Advantage: more in-depth investigation, shows change over time
• Disadvantage: more costly, dropout/death
5 STEPS OF THE SCIENTIFIC METHOD
4. Drawing Conclusions
• Replication
• Descriptive/Inferential Statistics
5. Evaluating the Theory
• Meta-analysis
• Submitting results for publication
INTRODUCTORY TERMINOLOGY FOR
SCIENTIFIC RESEARCH
•Variable: Any measurable condition that is controlled/observed in a
study; anything that can change.
•Theory: A broad idea or set of closely related ideas that attempt to
explain observations and to make predictions about future
observations.
•Hypothesis: An educated guess that derives logically from a theory;
a prediction that can be tested.
•Operational Definition: An objective description of how a variable is
going to be measured and observed.
•Participants or subjects: The organisms whose behavior is
systematically observed in a study.
RESEARCH METHODS
1. Descriptive Research:
• Naturalistic Observation
• Survey/Interview
• Case Study
• Archival Studies
NATURALISTIC OBSERVATION
Description: Observing the
participant in their natural habitat
without interaction
Advantages
Disadvantages
• Realistic picture of behavior • Difficult to remain unnoticed
• Good to start when little is
or unobtrusive
known about a phenomenon • Time consuming
SURVEY/INTERVIEW
Description: Use of questionnaires
to gain insight on an individual’s
attitudes or beliefs
Advantages
• Gathers data of difficult to
observe behaviors
• Large sample size
• Cost effective
• Relatively easy
Disadvantages
•
•
•
•
•
Wishful Thinking
Memory Lapses
Social Desirability Bias
Response Set
Wording Effect
CASE STUDY
Description: An in-depth
investigation on an individual
or cohort (small group)
Advantages
• In-depth investigation
• Helps formulate theories
• Unique cases
Disadvantages
• Subjectivity
• Researcher bias
• Lack of generalizability
ARCHIVAL RESEARCH
Description: Extracting
evidence from original records
or other researcher’s findings
Advantages
Disadvantages
• Researcher can not change • Researchers have little to no
data
control over information
• Cost effective
• Credibility of sources
RESEARCH METHODS
2. Correlational Research
CORRELATIONAL RESEARCH
• Research that examines the relationships
between variables, whose purpose is to
examine whether and how two variables
change together.
• There is NO manipulation of variables
• CANNOT imply a cause and effect
relationship between the variables
CORRELATIONAL RESEARCH
CORRELATION DOES NOT
EQUAL CAUSATION!
CORRELATIONAL RESEARCH
• Scientists have linked
• A local police chief in a
television-watching with
small Midwestern town
childhood obesity. According
finds that as ice cream
to a study in the Journal of
consumption increases, the
the American Academy of
crime rates increases. As
Pediatrics, the degree of
people eat less ice cream,
obesity rises 2 percent for
the crime rate decreases.
each hour of television
• The police chief concludes
viewed per week by those
that ice cream causes
aged 12 to 17.
crime.
• Scientists conclude that TV
watching makes you obese.
CORRELATIONAL RESEARCH
• Third variable problem: The circumstance
where a variable that has not been
measured accounts for the relationship
between two other variables.
CORRELATIONAL RESEARCH
• Research study designed to determine the degree
to which two variables are related to one another
• When two variables are related to each other, they
are co - related
• A correlation is the numerical index of degree of
relationship
• Correlation are expressed as a number between
0 and 1
• Can be negative or positive (-1 to +1)
• Numbers closer to 1 (+ or -) indicate a stronger
relationship
CORRELATIONAL RESEARCH
CORRELATIONAL RESEARCH
How to read a
Correlation Coefficient:
Correlation Coefficient: A statistical measure
of the relationship between two variables.
CORRELATIONAL RESEARCH
Strength
CORRELATIONAL RESEARCH
Direction
CORRELATIONAL RESEARCH
POSITIVE CORRELATIONS
3.5
3
2.5
Height
• As the value of one variable
increases (or decreases) so does
the value of the other variable.
• The closer the correlation
coefficient is to +1.0, the
stronger the relationship.
• A perfect positive correlation is
+1.0
• Direct relationship
2
1.5
1
0.5
0
0
2
Weight
4
CORRELATIONAL RESEARCH
• As the value of one variable
increases, the value of the other
variable decreases.
• The closer the correlation
coefficient is to -1.0, the stronger
the relationship.
• A perfect negative correlation is 1.0
• Inverse relationship
Temperature
NEGATIVE CORRELATIONS
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
0
2
4
Sweater Sales
6
CORRELATIONAL RESEARCH
• There is no relationship
whatsoever between the
two variables.
• The closer the correlation
coefficient is to 0, the
weaker the relationship.
• No relationship
Hours Spent Brushing Teeth
ZERO CORRELATION
2
1.5
1
0.5
0
0
2
4
6
Kitten Perpetrated Homicides
8
10
CORRELATIONAL RESEARCH
Coefficient of Determination: Percentage
of variation in one variable that can be
predicted based on the other variable.
• Square the correlation coefficient by itself
• Ex:
.70² = .70 * .70 = .49 = 49%
.24² = .24 * .24 = .057 = 5.7%
CORRELATIONAL RESEARCH
Description: determines the
degree to which two variables
are related to one another
Advantages
• No manipulation of variables
• Allows large populations to be
studied at one time
• Cost effective and Quick
• Enables investigation of difficult
variables to study
Disadvantages
• CANNOT show cause and effect
• Does not show the reason for the
relationship