Changes

'''Causal association''' is the presence or absence of a variable (e.g. [[smoking]]) is responsible for an increase or decrease in another variable (e.g. [[cancer]]). A change in exposure leads to a change in the outcome of interest.<ref>http://www.cdc.gov/vaccines/about/terms/glossary.htm#c</ref>

'''Causal association''' is an association between variables in which the presence or absence of a variable (e.g. [[smoking]]) is [[cause and effect|responsible]] for an increase or decrease in another variable (e.g. [[cancer]]). A change in exposure leads to a change in the outcome of interest.<ref>http://www.cdc.gov/vaccines/about/terms/glossary.htm#c</ref>

It is important to bear in mind that [[correlation is not causation]], or in other words that the change in one variable is not automatically the cause of the change in the other variable.  There could be other relationships at work instead, e.g., a common underlying cause for both, a reversal of cause and effect, or coincidence.  It is also important not to commit the [[Logical_fallacy#Post_hoc_ergo_propter_hoc|''post hoc'' fallacy]].

It is important to bear in mind that [[correlation is not causation]], or in other words that the change in one variable is not automatically the cause of the change in the other variable.  There could be other relationships at work instead, e.g., a common underlying cause for both, a reversal of cause and effect, or coincidence.  It is also important not to commit the [[Logical_fallacy#Post_hoc_ergo_propter_hoc|''post hoc'' fallacy]].