Restricted Cubic Splines were performed to explore the shape of association form of "U, inverted U,
L" shape and test linearity or non-linearity base on "Cox,Logistic,linear,quasipoisson" regression, and auto output Restricted Cubic Splines figures.
rcssci package could automatically draw RCS graphics with Y-axis "OR,HR,RR,beta".
The Restricted Cubic Splines method were based on
Suli Huang (2022)