Stata package

UDIAG

U/inverted-U tests

Tests and inference for U-shaped and inverted U-shaped relationships.

Version 1.1.1Stata 16+

Install in Stata

net install udiag, from("https://udiag-stata.pages.dev") replace
discard
help udiag

The peakgeom command remains available for existing scripts.

U/inverted-U tests

Turning-point inference

Estimate the stationary point and fitted response in quadratic models, with an optional moderator.

Shape tests

Use delta-method inference, Fieller sets, endpoint shape tests and bootstrap companion commands.

Additional diagnostics

Assess asymmetry and stability with companion diagnostic commands.

See the Stata help file for syntax, options, stored results and examples. Some companion analyses require additional estimation commands as described in their help files.

Code and documentation

Complete package ZIP Main command source Help file Installation manifest README

Research datasets and manuscript files are not included.