One-Tailed vs. Two-Tailed Tests (Does It Matter?)
One-tailed tests allow for the possibility of an effect in one direction. Two-tailed tests test for the possibility of an effect in two directions—positive and negative.
Simple as that concept may seem, there’s a lot of controversy around one-tailed vs. two-tailed testing. Articles like this one lambaste the shortcomings of one-tailed testing, saying that “unsophisticated users love them.”
On the flip side, some articles and discussions take a more balanced approach and say there’s a time and a place for both.
Let’s set the record straight.
