vitd.curve {SimVitD}

Generate Vitamin D curves

Description

Generates a vitamin D status profile curve for each individual in a group

Usage

vitd.curve( n = 1, type = c("placebo","fixed-dose","dynamic-dose"), start = 0, end = 1,  
    mu = 45, amplitude = 35, dyn.dose.thresh = 50, sd.mu = 5, sd.amplitude = 5, 
    sd.dyn.dose.thresh = 5, supp.dose = 20, supp.dose.rate = Inf, weight = 1, 
    sd.weight = 0, min.thresh = 10, north.hemi = TRUE, res = 40 )

Arguments

n

Number of curves to simulate.

type

One of "placebo", "fixed-dose", "dynamic-dose".

start

Time in units of years when trial started.

end

Time in units of years when trial ended.

mu

The mean level of 25OHD in the trial arm around which there is cosine variation.

amplitude

Amplitude of cosine function describing variation around mu

dyn.dose.thresh

Threshold for the concentration-controlled scheme.

sd.mu

Standard deviation levels around mean; this is the standard deviation of H in vignette.

sd.amplitude

Standard deviation of the amplitude.

sd.dyn.dose.thresh

Standard deviation of the participant retained concentration in the concentration-controlled trial.

supp.dose

The 25OHD nmol/l equivalent for dosage in fixed-dose supplementation.

supp.dose.rate

Concentration parameter for fixed-dose scheme uptake. Large values imply that all participants derive the same equivalent.

weight

For fixed-dose supplementation, this is the expected value of the proportion of the dose which is always utilized.

sd.weight

Standard deviation of weight

min.thresh

The minimum detectable threshold of 25OHD. Defaults to 10 nmol/l.

north.hemi

Summer/winter months as in the Northern Hemisphere if TRUE and Southern Hemisphere if FALSE.

res

Resolution parameter for plotting of vitamin D curves.

Value

vitd.curve returns an object of class vitd.curve. Curve parameter settings are returned. The slot curves give the curve specific parameters for each of the n generated curves. Additionally, time used for plotting gives time values passed to plot.vitd.curve.

Author(s)

Rebecca Mangan and Jason Wyse