For a balanced longitudinal data set a vector of the mean response and variances at defined time points is returned along with the correlation matrix of the responses across the time points.
1  summarybal(object, Y.col, times, use = "all.obs", na.rm, ...)

object 
a longitudinal data set in the balanced format. 
Y.col 
the column numbers of the longitudinal measurements at each design time point in the 
times 
a vector of unique time points of the longitudinal measurements. This does not have to be all of the study time points and may be a subset instead, but should match the columns defined in 
use 
an optional character string giving a method for computing
covariances in the presence of missing values. This must be (an
abbreviation of) one of the strings 
na.rm 
logical. Should missing values be removed? By default, 
... 
further arguments for the summary 
The function returns a list
with three elements: mean.vect
 a matrix with the time points in the first column and the mean response vector as the second column; variance
 the vector of variances for the response at the time points and cor.mtx
containing the correlation matrix of the responses between each pair of time points.
Ines Sousa (isousa@math.uminho.pt)
to.balanced
.
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Questions? Problems? Suggestions? Tweet to @rdrrHQ or email at ian@mutexlabs.com.
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