predict.gmusim: Predict the Shape Invariant Model with random effects...

In Zhiqiangcao/gmusim: Growth Modelling using a Shape Invariant Model with Random Effects

Description

Predict method for gmusim objects, based on predict.lme.

Usage

## S3 method for class 'gmusim'
predict(object, newdata, level = 1, ...)

Arguments

object	an object inheriting from class gmusim.
newdata	an optional data frame to be used for obtaining the predictions. It requires named columns for x, z and for id if level = 1, matching the names in object. Note that values of covariates z should be centralizated. By default their values are set to the mean so when level = 0 the prediction represents the mean curve. Note that factors are coded as instrumental variables for each level, corresponding to the fixed effect coefficients in the model, so their names need the level appending..
level	an optional integer giving the level of grouping to be used in obtaining the predictions, level 0 corresponding to the population predictions. Defaults to level 1.
...	other optional arguments, including na.action and naPattern.

Details

Note that if level = 1, this function calculates predicton for every measurment of individuals; if level = 0, it calculates mean value of individuals' measurements.

Value

A vector of the predictions.

Author(s)

Zhiqiang Cao [e-mail], Man-Yu Wong [e-mail]

Examples

require(sitar)
data(heights)
x <- heights$age
y <- heights$height
men <- heights$men
id <- heights$id
df <- 5
#since negative value are censored, here use absolute value
z <- data.frame(z1=abs(men))
p <- 1
n <- length(x)
## fit sitar model with covariates
resu1 <- gmusim_both(x,y,z,p,n,id,df)
## predictions at level = 0
on.exit(detach(resu1))
eval(parse(text = "attach(resu1)"))
predict(resu1, newdata=data.frame(x=6:15,z1=rep(mean(men),10)), level=0)
## predictions at level = 1 for all subjects
newd <- data.frame(x=heights$age,z1=abs(men)-mean(abs(men)),id=id)
on.exit(detach(resu1))
eval(parse(text = "attach(resu1)"))
fitted.values <- predict(resu1, newdata=newd, level=1)

Zhiqiangcao/gmusim documentation built on May 10, 2019, 1:58 a.m.