Last updated: 2017 11 28
This app runs the u-shape test introduced by Simonsohn (2017 .pdf).
It estimates an interrupted regression, that is, a regression with two separate slopes, for the
predictor hypothesized to have a u-shaped effect. If both slopes have opposite sign,
and are individually statistically significant, the test rejects the null hypothesis that
there is no u-shaped (nor inverted u-shaped) effect.
Or, download the R Code behind the ap and run it on your computer.