This document discusses two types of relationships - predictive relationships, where one variable directly causes or predicts another variable, and arbitrary relationships, where it is unclear which variable influences the other. Predictive relationships have a clear influence between variables, like daily temperature predicting sunscreen sales, while arbitrary relationships are less clear on the direction of influence, such as whether wealth impacts education or vice versa.

1. Unless your relationship problem specifies a
predictive relationship (with one variable
causing or predicting directly another variable)
then the problem is most likely arbitrary (where
it is unclear the strength or predictive
relationship between two variables).
Predictive or Arbitrary Relationships
Predictive
One variable clearly influences or
predicts another variable (e.g., daily
temperature predicts sunscreen sales)
Arbitrary
It is unclear which variable causes or
predicts which variable (e.g., does
wealth impact the amount of education
you have or does the amount of
education you have impact your
wealth?)