Stanovich Ch 5:
It is not the strength, but the nature of the relationship that is relevant
(giving out toasters will not make people use contraceptives). Two variables
may be associated without having a causal relationship.
The presence of a correlation does not necessarily imply causation
Goldberger ate poo, didn't get pellagra, created the necessary conditions for
it to be transmitted and it wasn’t therefore it cannot be caused by feces,
Goldberg must be right about it being caused by poor diet. Proved his
condition by using 2 groups of prisoners, giving them the two types of diets,
people with the poor diet got pellagra.
Important to approach correlational evidence with certain skepticism.
Third variable problem: the fact that the correlation between the two
variables - ie. pellagra and sewage conditions - may not indicate a direct
causal path between them, but may arise because both variables are related
to a third variable - in this case, diet - that has not even been measured.
Correlations like that between sewage and pellagra are often termed spurious
correlations: correlations that arise not because a causal link exists between
the 2 variables that are measured, but because both variables are related to
the third variable.
Can factor out variables using complex math to see the direct relationships
between certain variables, when potential spurious variables are removed.
For example: is university attendance related to socioeconomic status, a
potential third variable is academic ability, if we partial out academic ability
the correlation between university attendance and socioeconomic status may
disappear. When potential spurious variables are removed but still appear to
have an affect that tells us something too, maybe they are important after all.
Basically, if you have a hypothesis, anything that can be a spurious variable
has to be partialed out.
Correlations can also be misinterpreted; erratic eye movements were
thought to cause poor reading skills, when in fact, slow recognition of words
and difficulties with comprehension lead to erratic eye movements. (Casual
relationship that was int