tptest: Universal Turning Point and Inflection Point Tests

Performs turning point and inflection point tests for U-shaped and inverse U-shaped relationships in regression models. Implements the Sasabuchi (1980) test as extended by Lind and Mehlum (2010) with support for quadratic, cubic, log-quadratic, and inverse functional forms. Features include delta-method standard errors, Fieller confidence intervals, Simonsohn (2018) two-lines test, and parametric bootstrap. Designed for post-estimation analysis of linear models, panel models, and quantile regression. References: Lind and Mehlum (2010) <doi:10.1111/j.1468-0084.2009.00569.x>; Sasabuchi (1980); Fieller (1954) <doi:10.1111/j.2517-6161.1954.tb00159.x>.

Version:	1.0.3
Depends:	R (≥ 4.0.0)
Imports:	stats, graphics
Suggests:	testthat (≥ 3.0.0), knitr, rmarkdown, lmtest, sandwich, plm, quantreg
Published:	2026-04-09
DOI:	10.32614/CRAN.package.tptest
Author:	Muhammad Alkhalaf [aut, cre, cph]
Maintainer:	Muhammad Alkhalaf <muhammedalkhalaf at gmail.com>
BugReports:	https://github.com/muhammedalkhalaf/tptest/issues
License:	GPL-3
URL:	https://github.com/muhammedalkhalaf/tptest
NeedsCompilation:	no
Materials:	README, NEWS
CRAN checks:	tptest results

Documentation:

Reference manual:

tptest.html , tptest.pdf

Downloads:

Package source:	tptest_1.0.3.tar.gz
Windows binaries:	r-devel: tptest_1.0.3.zip, r-release: tptest_1.0.3.zip, r-oldrel: tptest_1.0.3.zip
macOS binaries:	r-release (arm64): not available, r-oldrel (arm64): not available, r-release (x86_64): tptest_1.0.3.tgz, r-oldrel (x86_64): tptest_1.0.3.tgz

Linking:

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