http://www.pewresearch.org/fact-tank/2015/09/16/the-art-and-science-of-the-scatterplot/?utm_source=Pew+Research+Center&utm_campaign=c236709ce6-Weekly_Sept_17_20159_16_2015&utm_medium=email&utm_term=0_3e953b9b70-c236709ce6-399726609

"One important point to understand is that the scatterplot shows correlation, not causality, said Pew Research Center’s art director, Diana Yoo. … While sometimes people see a causal relationship, the chart only shows an association…"