Opinion surveys made by less competent agencies should be carefully examined for possible misrepresentations. Imputing Causation When an actual statistical association is found, the next step is to determine which is cause and which is effect. A and B are actually unrelated - we have a spurious association. The difficult question of determining what causes what is only begun when a valid association is established. A coefficient of correlation is a particular kind of measure of association used when associating two or more quantitative variables.
Positive correlation is when both variables rise or fall together.
In negative or inverse correlation, the two variables move in opposite directions.