To be used in predict.mfp2().
calculate_standard_error(model, X, xref = NULL)Standard error.
fitted mfp2 object.
transformed input matrix with variables of interest for partial predictor.
transformed reference value for variable of interest. Default is
NULL, in which case this function computes standard errors without reference
values.
See pages 91-92 and following in the book by Royston and Sauerbrei 2008 for the formulas and mathematical details.
Royston, P. and Sauerbrei, W., 2008. Multivariable Model - Building:
A Pragmatic Approach to Regression Anaylsis based on Fractional Polynomials
for Modelling Continuous Variables. John Wiley & Sons.