Dear R-users
   
  I have problems using lme
   
  The model i want to fit can be viewed as a two-level bivariate model 
 
Two-level bivariate: bivariate (S coded as -1,T coded as 1) endpoint within trial
  OR
  It can equivalently be considered as a three-level model.Three-level: endpoint within patient, patient within trial. 
   
My code tries to model the levels through a RANDOM statement and a within group correlation structure.
 
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Now then, i used the following R code:
  bm <- lme (outcome~ -1 + as.factor(endpoint)+ as.factor(endpoint):trt, data=datt,
       random=~-1 + as.factor(endpoint) + as.factor(endpoint):trt |as.factor(Trial),
       corr = corSymm(form~-1+as.factor(endpoint)|trial/subject))
  
I beleive the fixed effects part of the code is okay. My intention for the random effects part is to estimate an intercept and treatment effect for each endpoint at the trial level. The correlation structure should produce a within correlation matrix for the enpoints at the subject level.
   
  Thus the random effects matrix is 4 by 4 and the within correlation matrix is 2 by 2
  When i run the code in R, i get the following error message
   
  "Error in Initialize.corSymm(X[[2]], ...) : 
        Initial value for corSymm parameters of wrong dimension"
   
  I hope someone will correct my codes .
   
  Kind regards
  Pryseley
   
   
  

 

		
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