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Chapter 2

PSY230H1 Chapter Notes - Chapter 2: Random Assignment, Dependent And Independent Variables, Takers

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Amanda Sharples

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Chapter 2: Personality Research Models
The Hypothesis-Testing Approach
Theory: a general statement about the relationship between constructs/events "
Some are very broad (e.g. Freud’s psychoanalytic theory used to explain psychological
disorders, as well as why certain jokes are funny) "
However, personality researchers typically work w/ theories considerably narrower in
application easier to think of larger theories as collections of more specific theories that
share certain assumptions"
Characteristics of a good theory:"
1. Parsimonious "
Law of parsimony: simplest theory that can explain phenomenon is best "
2. Useful "
Can generate testable hypotheses need to be able to lend itself to scientific
investigation "
Theories themselves are never tested; hypotheses are derived from the theories that can
then be tested in research "
Hypothesis: formal prediction about relationship between two or more variables that’s
logically derived from the theory "
E.g. why do some people frequently suer from feelings of loneliness, whereas others
rarely feel lonely? theory: lonely people lack social skills necessary to develop &
maintain satisfying relationships prediction: consistently lonely people expected to
make fewer attempts to initiate conversations test"
Theories are never proved/disproved, only more/less supported by research & more/less
useful to scientists "
Experimental variables: "
1. Independent variable (treatment variable): determines how groups in experiment are
divided (i.e. when participants are randomly assigned to di experimental conditions) "
Found on x-axis "
Often what’s manipulated by experimenter "
E.g. amount of a drug each group receives, type of story each group reads, level of
anxiety created in each group (e.g. Group A is told to give a speech in front of a
dozen critical people, while Group B is told to give a speech in front of a few
supportive people & Group C knows nothing about speech) "
2. Dependent variable (outcome variable): measured by the investigator & used to
compare experimental groups "
Found on y-axis "
If experiment is well-designed dierences among groups on the dependent
variable attributed to di levels of independent variable "
E.g. returning to anxiety example hypothesis: people reduce anxiety about
upcoming events by obtaining as much info about the situation as possible
independent variable: level of anxiety dependent variable: how many questions
they ask the experimenter about upcoming event "
Dierence in dependent variable (# questions asked) attributed to di levels of
independent variable (anxiety) "
Researchers typically use > 1 independent variable (e.g. randomly assign participants to
anxiety/no-anxiety group identify shy & non-shy w/in each of these groups) "
Interaction: how one independent variable aects the dependent variable depends on the
other independent variable "
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