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 (may not be active yet) |
| 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:
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