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Unformatted text preview: Priests ↑ → Prostitutes ↑
(this seems too silly to consider) 29 Possibility
As the number of prostitutes increase in a community,
this causes the number of priests to increase.
Prostitutes ↑ → Priests ↑
(more sin requires more repentance?) 30 Possibility
Involvement of a 3rd Variable?
Some other variable influences both the number of
priests and the number of prostitutes.
(as a city gets larger, the number of priests AND prostitutes
increase, but one does not cause the other) Correlations provide no information
about causal relationships!!
31 Are the only type of research study that can
clearly establish a CAUSAL RELATIONSHIP
By directly manipulating one variable to see
whether that causes a change
in another variable. 32 Some
The variable that the researcher manipulates.
The variable that gets measured to determine whether
manipulating the Independent Variable
has any effect. 33 Some
BetweenBetween-Subject Experimental Design
Different participants contribute data for each level of
the Independent Variable.
Within-Subjects Experimental Design
WithinThe same participants contribute data for each level of
the Independent Variable. 34 An
Room temperature vs. 20° Higher
# of word math problems solved in 15-minutes 35 36 Major
A Major Advantage
If done properly, a researcher can firmly
establish that one variable
has a causal influence on another variable.
…but, there are a lot of things that can
render an experiment INVALID
INVALID. 37 Confounding Variables
Other factors that could vary along with the
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This note was uploaded on 01/16/2014 for the course PSYCH 1200 taught by Professor Dougalards-tomalin during the Fall '13 term at Manitoba.
- Fall '13