PSY100H1 Chapter Notes - Chapter 2: Participant Observation, Random Assignment, Longitudinal Study
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Lecture 2: Research Methods in Psychology
• Most research relies on either correlations or experiments. With correlations, researchers
measure variables as they naturally occur in people and compute the degree to which two
variables go together. With experiments, researchers actively make changes in one variable
and watch for changes in another variable.
• Other types of methods include longitudinal and quasi-experimental designs.
• Many factors, including practical constraints, determine the type of methods researchers
• One of the important steps in scientific inquiry is to test our research questions, otherwise
known as hypotheses.
• There are many methods, which will depend on the type of questions you are asking and
what resources are available to you, to test hypotheses in psychological research. However,
all methods have limitations, which is why the best research uses a variety of methods.
• Most psychological research can be divided into two types: experimental and correlational
• Psychologists measure many abstract concepts, such as happiness and intelligence, by
beginning with operational definitions (the definition of a conceptual variable within a
study) of the concepts.
• In an experiment, researchers manipulate, or cause changes, in the independent variable
(the variable under the experimenter’s control), and observe or measure any impact of those
changes in the dependent variable (the variable not under the experimenter’s control).
• The dependent variable “depends” on what happens to the independent variable.
• The most important thing about experiments is random assignment (assigning participants
to receive different conditions of an experiment by chance). Participants don’t get to pick
which condition they are in (e.g., participants didn’t choose whether they were supposed to
spend the money on themselves versus others)—Participants will be relatively equivalent on
all factors--the only difference between the two groups is the independent variable-- the
independent variable is the cause of any observable difference.
• Confounds (that need to be avoided) are things that could undermine your ability to draw
• Placebo effect (an example of a confound) is when receiving special treatment or something
new affects human behaviors.
• Participant demand is When participants behave in a way that they think the experimenter
wants them to behave—occur unintentionally
• Experimenter expectations is when the experimenter’s expectations influence the outcome
of a study.
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• One way to prevent these confounds from affecting the results of a study is to use a double-
blind procedure. In a double-blind procedure, neither the participant nor the experimenter
knows which condition the participant is in.
• Correlational research is when scientists passively observe and measure phenomena. In
correlational research, we identify patterns of relationships but we usually cannot infer what
causes what, and we can examine only two variables at a time, no more and no less.
More details about the correlation
• The association between two variables can be summarized statistically using the correlation
coefficient (abbreviated as r).
• A correlation coefficient provides information about the direction and strength of the
association between two variables.
• With a positive correlation, the two variables move in same direction (go up or down
together). A negative correlation is one in which the two variables move in opposite
directions (as one variable goes up, the other goes down).
• If an association has many exceptions, it is considered a weak correlation. If an association
has few or no exceptions, it is considered a strong correlation. A strong correlation is one in
which the two variables almost always go together.
• The r value of a strong correlation will have a high absolute value. The r value for a weak
correlation will have a low absolute value. If two variables are so weakly related as to be
unrelated, we say they are uncorrelated, and the r value will be zero or very close to zero.
Problem with the correlation
• correlation does not mean causation.
• Qualitative designs, including participant observation, case studies, and narrative analysis
are examples of such methodologies.
• Participant observation is a distinct methodology that involves the researcher embedding
him- or herself into a group in order to study its dynamics.
• Another qualitative method for research is the case study, which involves an intensive
examination of specific individuals or specific contexts. a case study is really the only type
of methodology suitable for researching this brain injury.
• The final qualitative method to be discussed in this section is narrative analysis. Narrative
analysis centers around the study of stories and personal accounts of people, groups, or
cultures. A researcher will examine people’s personal testimonies through written, audio-
recorded and video-recorded in order to learn more about the psychology of those
individuals or groups, and study the way that people convey a story can provide insight into
• A quasi-experimental design is similar to experimental research, except that random
assignment to conditions is not used but rely on existing group memberships
• Longitudinal studies track the same people over time.
• Longitudinal studies like this provide valuable evidence for testing many theories in
psychology, but they can be quite costly to conduct.
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