fp.power {coxphw} R Documentation

## Provides Fractional Polynomials as Accessible Function

### Description

Provides fractional polynomials as accessible function.

### Usage

 fp.power(z, a, b = NULL)  

### Arguments

 z a scalar or vector of positive numerical values. a first power. b optional second power.

### Details

The function returns fp(a) of z (and optionally fp(b) of z).

### Value

A matrix with one or two columns (if a second power b was specified), and number of rows equal to the length of z. The columns are sorted by descending power.

Georg Heinze

### References

Royston P and Altman D (1994). Regression Using Fractional Polynomials of Continuous Covariates: Parsimonious Parametric Modelling. J R STAT SOC C-APPL 43, 429-467.

Royston P and Sauerbrei W (2008). Multivariable Model-Building. A Pragmatic Approach to Regression Analysis Based on Fractional Polynomials for Modelling Continuous Variables. Wiley, Chichester, UK.

coxphw
fp.power(z = c(1, 4, 6), a = 1)