fp.power {coxphw} | R Documentation |
Provides fractional polynomials as accessible function.
fp.power(z, a, b = NULL)
z |
a scalar or vector of positive numerical values. |
a |
first power. |
b |
optional second power. |
The function returns fp(a
) of z
(and optionally fp(b)
of z
).
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
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.
fp.power(z = c(1, 4, 6), a = 1) fp.power(z = c(1, 4, 6), a = 0.5) fp.power(z = c(1, 4, 6), a = 0.5, b = 0.5) fp.power(z = c(1, 4, 6), a = 0, b = 2)