potthoff {growth}

Potthoff and Roy Growth Curve Model

Description

potthoff fits the Potthoff and Roy repeated measurements growth curve model with unstructured covariance matrix to completely balanced data.

Usage

potthoff(response, x = NULL, ccov = NULL, times = NULL, torder = 0,
  orthogonal = TRUE)

Arguments

response

A matrix or dataframe of response values.

x

A matrix defining the complete intersubject differences or a Wilkinson and Rogers formula that will create one.

ccov

A matrix of columns of the baseline covariates to be actually fitted, with one row per individual or a W&R formula that will create one.

times

A vector of unequally spaced times when they are the same for all individuals. Not necessary if equally spaced.

torder

Order of the polynomial in time to be fitted. If non-numeric, the full model in time is fitted.

orthogonal

If TRUE, uses orthogonal polynomials for time, otherwise only centres times at their mean.

Value

A list of class potthoff is returned.

Author(s)

J.K. Lindsey

See Also

carma, elliptic, lm.

Examples

y <- matrix(rnorm(40),ncol=5)
x <- gl(2,4)
# full model with treatment effect
potthoff(y, ~x, torder="f", ccov=~x)
# no time trend with treatment effect
potthoff(y, ~x, torder=0, ccov=~x)
# quadratic time with treatment effect
potthoff(y, ~x, torder=2, ccov=~x)
# full model without treatment effect
potthoff(y, ~x, torder="f")
# linear time without treatment effect
potthoff(y, ~x, torder=1)