fracpol: Fractional Polynomials
In dosresmeta: Multivariate Dose-Response Meta-Analysis

Description Usage Arguments Details Value Author(s) References See Also Examples

Two-order fractional polynomials transformation for continuous covariates.

1	fracpol(x, p = c(1, 1), shift, scale, scaling = TRUE)

`x`	a numeric vector.
`p`	a vector of length 2 with the powers of x to be included.
`shift`	optional scalar representing the shift, if `scaling = TRUE`. If not specified it is se internally equal to 0.
`scale`	optional scalar representing the scale, if `scaling = TRUE`. If not specified it is se internally equal to 1.
`scaling`	a logical indicating if the measurements are scaled prior to model fitting.

The fracpol is based on the FP function in the mboost package. See help(FP) for more details.

A matrix including the trasformations corresponding to the input values.

Alessio Crippa, alessio.crippa@ki.se

Royston, Patrick, and Douglas G. Altman. "Regression using fractional polynomials of continuous covariates: parsimonious parametric modelling." Applied Statistics (1994): 429-467.

mboost, rcs.eval

## Load data and run the model
data("alcohol_cvd")

with(alcohol_cvd, fracpol(dose, p = c(.5, .5)))

model <- dosresmeta(formula = logrr ~ fracpol(dose, p = c(.5, .5)), type = type, id = id,
                    se = se, cases = cases, n = n, data = alcohol_cvd) 
                    
## Test for significance of the overall dose-response association
waldtest(b = coef(model), Sigma = vcov(model), Terms = 1:nrow(vcov(model)))