Two-lines test

(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.

If you know R you may want to:

If you don't know R, or you're feeling lazy. Use this web app

If you don't have a file but want to check things out, download this datafile and then upload it.

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