R: Natural cubic spline basis

basis {flexsurv} | R Documentation

## Natural cubic spline basis

### Description

Compute a basis for a natural cubic spline, using the parameterisation described by Royston and Parmar (2002). Used for flexible parametric survival models.

### Usage

    basis(knots, x)

### Arguments

`knots` | Vector of knot locations in increasing order, including the boundary knots at the beginning and end.
`x` | Vector of ordinates to compute the basis for.

### Details

The exact formula for the basis is given in `flexsurvspline`.

### Value

A matrix with one row for each ordinate and one column for each knot.

`basis` returns the basis, and `dbasis` returns its derivative with respect to `x`.

`fss` and `dfss` are the same, but with the order of the arguments swapped around for consistency with similar functions in other R packages.

### Author(s)

Christopher Jackson <chris.jackson@mrc-bsu.cam.ac.uk>

### References

Royston, P. and Parmar, M. (2002). Flexible parametric proportional-hazards and proportional-odds models for censored survival data, with application to prognostic modelling and estimation of treatment effects. Statistics in Medicine 21(1):2175-2197.

### See Also

`flexsurvspline`.

[Package flexsurv version 2.1 Index]