A study done by law student Tyler Vigan showed a moderate to strong correlation between the number of movies Nicolas Cage releases in a year and the number of drownings in swimming pools in the same y...A study done by law student Tyler Vigan showed a moderate to strong correlation between the number of movies Nicolas Cage releases in a year and the number of drownings in swimming pools in the same year. So in this example, urbanization is the cause of both variables increasing. (This is an example of a confounding variable). A confounding or lurking variable is a variable that is not known to the researcher, but affects the results of the study.