|image found here. source?|
* possibly arbitrary.
** almost certainly arbitrary.
*** Statistical jargon alert: "Fishing" is a word for the practice of looking at your data in so many different ways that you eventually find an association simply by chance, and then reporting that association as if it was what you were looking for in the first place. See also: bullshit, cheating, lying, multiple comparisons.
Found on NYT, but the source of the graphic is not clear. I sure as hell wouldn't put my name on it.