An implementation of Lind and Mehlum's (2010) tools:::Rd_expr_doi("10.1111/j.1468-0084.2009.00569.x") Utest to test for the presence of a U shaped or inverted U shaped relationship between variables in (generalized) linear models. It also implements a test of upward/downward sloping relationships at the lower and upper boundary of the data range.
Maintainer: Jo Thori Lind j.t.lind@econ.uio.no (ORCID)
Authors:
Halvor Mehlum halvor.mehlum@econ.uio.no
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