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Chapter 5: Correlation and
Causation
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Correlation does not mean causation ·
Two problems in interpreting correlational
research: |
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Third-Variable problem: A correlation between two
variables does not automatically indicate a direct relationship. It could be a result of a third unmeasured
variable. |
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Directionality problem: the presence of the
correlation among two variables does not necessarily indicate the direction
of that relationship. |
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Selection Bias: relationships between environmental
variables and certain subjects that may occur when individuals with different
characteristics (behavioral, biological and psychological) select different
types of environments. |
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Spurious correlation: correlations that arise because
both variables are related to a third variable (not because of a causal link between
the two variables) |
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Examples: |
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**Third-Variable problem: Toasters as Contraceptives? |
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Research has shown the strongest correlation was between
contraceptive use and number of electrical appliances in the home (Li,
1975). Should schools start a program
handing out free appliances? Implying
a causal relationship? No. People from higher SES families and education
level could possibly have more electrical appliances. Education level could affect the
correlation because it is related to contraceptive use, and SES. There could be other mediating variables. |
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The two variables may be associated but not have a causal
relationship. |
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**Directionality problem: Self-Esteem and Behavior |
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Research has shown a correlation between school achievement
problems, drug abuse, teenage pregnancy and other problem behaviors were the
result of low self-esteem (Dawes, 1994; Kahne,
1996). Low self-esteem led to problem
behaviors and high self-esteem led to achievements and accomplishments in
education and other domains, but the relationship can be reverse. Accomplishments and achievements could lead
to high self-esteem. |
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The direction of the relationship could be A à B or Bà A so it is important
to be careful how the relationship is defined. |
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