Anyone who has taken an intro to psych
or a statistics class has heard the old adage, "correlation does not imply
causation." Just because two trends seem to fluctuate in tandem, this rule
posits, that doesn’t prove that they are meaningfully related to one another.
Correlation is a statistical
measure that describes the size and direction of a relationship between two or
more variables.
Causation indicates that one event is the
result of the occurrence of the other event; i.e. there is a causal
relationship between the two events.
Causality is the area of statistics that
is commonly misunderstood and misused by people in the mistaken belief that
because the data shows a correlation that there is necessarily an underlying
causal relationship.
A good example is that the rate of drowning
on Sydney’s beaches is positively correlated to the sale of ice cream.
An incorrect conclusion is that “the
consumption of ice cream leads to drowning”. More likely the reason would be
that both drowning and ice cream sales are positively affected by hot weather;
more people are at the beach and more ice creams are sold- correlation does not
imply causation!.
A few examples from recent articles and
headlines:
“Spiritual people are more likely to be
mentally ill” -The Daily Mail
“...children whose parents smoked
were more likely to exhibit delinquent behaviour”- The Guardian
“People who have large weddings are less
likely to get divorced”- Psychology Today
“Men and women who eat more of the
sweets are also likely to be depressed”-LA times
“Coffee may
prevent depression, scientists say”-BBC
Don’t be duped by Facebook trends-
correlation does not imply causation