basis | R Documentation |

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

basis(knots, x)

`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. |

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

.

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.

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

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.

`flexsurvspline`

.

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