dosresmeta (version 2.0.1)

fracpol: Fractional Polynomials

Description

Two-order fractional polynomials transformation for continuous covariates.

Usage

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

Value

A matrix including the trasformations corresponding to the input values.

Arguments

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.

Author

Alessio Crippa,

Details

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

References

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

See Also

mboost, rcs.eval

Examples

## 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)))