All,
 
I have a repeated measures data frame and was wondering if the
covariance matrix can be 
calculated via some created indexing or built-in R function.
 
Specifically, say there are 3 variables, where potassium concentration
is measured 6 times on each patient.
Patient number (discrete)
Time (1 to 6, discrete)
Potassium (continuous variable)
 
I want the covariance/correlation matrix for the cov/corr between
Potassium at time i and time j.
 
Is this possible in the current dataframe format?  Or do I have to
define new varialbes, say Time i and Time j, 
and then compute the cov/corr between Time i and Time j for all
combinations?   
 
Cheers,
Dave
 
 
 
 
David Afshartous, PhD
University of Miami
School of Business
Rm KE-408
Coral Gables, FL 33124
 

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