This is the class of visual inference orthogonal polynomial linear model, inherited from VI_MODEL.
See also
Parent class: VI_MODEL
New attributes: POLY_MODEL$formula,
POLY_MODEL$null_formula, POLY_MODEL$alt_formula, POLY_MODEL$z_formula,
POLY_MODEL$raw_z_formula
New methods: POLY_MODEL$..init.., POLY_MODEL$test, POLY_MODEL$E,
POLY_MODEL$sample_effect_size, POLY_MODEL$set_prm, POLY_MODEL$hermite