(version 0.32 - beta testing)
Last updated: 2018 03 20 (see how the app has changed over time)
This app runs the u-shape test introduced by Simonsohn (2017 .pdf).
In particular, it estimates an interrupted regression, that is, a regression with two separate slopes, for the
predictor hypothesized to have a u-shaped effect. The breakpoint is set using the "Robin Hood" algorithm,
seeking to obtain higher power to detect a u-shape if it is present. If the resulting two 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.
Thanks for using the two-lines test