Research Methods-PART TWO
An outline to guide student notes
I. Types of Psychological Research Methods
A. Descriptive studies
To systematically and objectively describe the characteristics of individuals or groups
B. Correlational studies
To determine and describe the strength of relationship (if any) between two or more variables (events or
characteristics)
C. Experiments
The deepest explanation of all methods used to determine if the manipulation of the independent variable
causes the predicted change in the dependent variable
D. Depth of Explanation
II. Descriptive Studies:
A. Case Studies -Observe one or a very few subjects in great depth, usually over a
long period of time
1. Advantage: The only method appropriate for very unusual cases
2. Disadvantage: Problems with generalizing the results
B. Naturalistic Observation-Observe behavior in its natural setting, attempt to
avoid influencing or controlling it
1. Advantage: Good way to collect normative data
2. Disadvantage: Must wait for the behavior to occur naturally
3. Note lecture ‘call out’ on defining conceptualization and operationalization of
variables
C. Surveys -Collect data from groups of people using questionnaires or
interviews. Data is useless unless sample is representative.
1. Advantage: Can collect information such as attitudes and beliefs
2. Disadvantage: Subjects may lie or mislead
D. Standardized Tests
Require people to answer a series of written or oral questions
Individual’s test score is totaled to yield a single score
This single overall score is compared to the scores of many similar people
E. Archival Records
A form of research that relies on existing records of past behavior
III. Correlational Research
A. Goal of describing the strength of the relationship between two or more
characteristics (variables)
1. Variables -Any characteristic on which individuals differ.
i. Examples: Aggressiveness, intelligence, self-esteem,.
2. The more highly two variables are related, the more we can
predict one from the other.
B. Correlation Coefficient
1. Statistical measure of the extent to which two variables are
associated
2. r varies from -1.0 to +1.0 (-.9, -.64, +.55, +. 76)
a. Strength
events or
Higher absolute values, indicate stronger relationships
(-.91 > +.66).
Direction
Positive
Higher scores on VAR1 go with higher scores on VAR2
Negative
Higher scores on VAR1 go with lower scores on VAR2
C.. Correlation does not imply causation.
1.Three possible causal explanations
Start with 3 variables, (X, Y, & Z) where X and Y are correlated:
X might cause Y
Y might cause X
X might be correlated with Y, which causes Z
Correlations show patterns, not causes
2.Advantages
Description and prediction possible
3. Disadvantages
No control over variables
Cannot imply causality
IV. Experimental Method
A carefully regulated procedure in which one or more factors (independent
variables) believed to
influence the behavior being studied (dependent
variable) are manipulated and all other factors are held
constant.
A. Determining cause by measuring effect
1. Independent Variable (IV)
a. the variable being manipulated or controlled by the
experimenter (to see if it causes an effect)
b. Independent variable (IV) must have at least two levels:
1. Experimental or treatment condition (experimental
group)
2. Control condition (control group)
2. Dependent Variable (DV)
3. Random Assignment - Assignment of subjects from the representative sample to
experimental and control groups by chance
4 . Representative Sample - (opposite of sampling bias)
The characteristics of the participants in the experimental and control
groups corresponds closely to the characteristics of the larger
population being studied
B. Experimental Research Design Examples
A. Example 1
B. Example 2
C. Summary Note
1. A hypothesis is made (experimental hypothesis = a prediction)
2. The population is identified
3. A representative sample is selected
4. The representative sample is randomly assigned to the experimental
condition or the control condition.
5. The investigator varies some factors (independent variable)
Experimental groups get the different values of the independent variables. Control groups do not
6. The investigator keeps some factors constant
7. The investigator measures the effects on the dependent variable.
8. Dependent variables supposedly affected by independent variables.
9. Statistical Significance established
10. Conclusions about causality are possible due to the controlled methods.
11. Replication/repeating research strategies to confirm original findings are possible.
C. Cautions : Bias
Bias can affect the way an experimenter designs a study, collects data, or interprets results
1. Types of observer bias:
a. . Personal bias
i. . The influence of the experimenter’s own beliefs, preferences assumptions,
prejudices, on the outcome of the research
ii. Often not obvious to individual
iii.. May notice only evidence confirming their hypothesis
and ignore contradictory evidence
.b. Expectancy bias
The influence of one’s expectations on one’s observations and
looking for certain outcomes.
2.. Participant bias
Placebo effect
Occurs when participants’ expectations, rather than the
experimental treatment, produce the desired outcome
Placebo bias – When a subject in an experiment receives no
treatment but still believes that the treatment is working
Placebo – Substances or events that appear to be the real thing
(e.g. drugs) but are not. Placebos cause a placebo effect in some people that experience them.
3. Controlling Bias
a. Double blind study
A study in which neither the subjects nor the experimenters know which subjects are in
the experimental group and which are in the control group until the results are
calculated
b. Single blind study
Keeping subjects uninformed about the purpose of a study so they are less likely to
perform to the researchers expectations.
c. Deception and debriefing
Provide subjects with a full and honest account of the true purposes and assumptions
of the research study as required by American Psychological Association when
deception is used
D. Confounding Variables
1. Researchers must also attempt to control extraneous or confounding
variables
2. Any variable(s) other than the independent variable that seem likely to
influence the dependent variable in a specific study.
3. Use of random assignment helps to avoid extraneous variables
E. What is the Scientific Method?
•
The scientific method is an approach to knowledge that relies on a systematic method of asking
questions, generating hypothesis, collecting data, and interpreting the findings.
Scientific method –
A five-step process for empirical investigation of a hypothesis under conditions designed to control biases and
subjective judgments
•
The First Step of the Scientific Method is______________________________________
Define: Hypothesis
Operational Definition
The Second Step of the Scientific Method is____________________________________
Define: Independent Variable
Randomization
Experimental Group
Control Group
The Third Step of the Scientific Method is _____________________________________
Define; Data
Dependent Variable
The Fourth Step of the Scientific Method is ____________________________________
The Fifth Step of the Scientific Method is _____________________________________
F. Thinking Critically About Behavior
•Making sense of behavior claims
•Find out how important terms are defined and measured
•Understand the nature of the sample before you generalize
•Do not predict individual behavior from group results
•Resist interpreting the results of a single study as definitive
•Differentiate correlation research from experimental research
•Evaluate the credibility of the source
•Be skeptical of simplistic claims
•A single study usually is not the defining word about an issue or problem