apv_se {sitar}

Bootstrap standard errors for SITAR peak velocity and age at peak velocity

Description

apv_se bootstraps a SITAR model to generate standard errors for age at peak velocity (apv) and peak velocity (pv).

Usage

apv_se(object, fun = getPeak, nboot = 10, seed = NULL, plot = FALSE, ...)

Arguments

object

SITAR model.

fun

function to extract apv and pv from velocity curve (default getPeak), alternative getTakeoff or getTrough.

nboot

number of bootstrap samples (default 10).

seed

integer to initialize the random number generator (default NULL).

plot

logical to control plotting (default FALSE).

...

optional arguments defining the velocity curve to be bootstrapped (plot.sitar arguments xfun, yfun, subset, ns or abc), and graphical par parameters.

Details

If plot is TRUE, the original velocity curve is plotted along with each bootstrap sample's pv versus apv.

Value

a 2x2 array giving the mean and standard error of apv and pv, with attribute "bs" a tibble containing the bootstrap estimates of apv and pv, with NAs removed.

Author(s)

Tim Cole [e-mail]

Examples

data(heights)
## fit sitar model for height
model <- sitar(x = age, y = height, id = id, data = heights, df = 4)

## bootstrap standard errors for age at peak velocity and peak velocity
output <- apv_se(model, nboot=3, seed=111, plot=TRUE)