[R-sig-ME] LME4 to MCMCglmm

tw at netstorm.be tw at netstorm.be
Fri May 4 10:04:10 CEST 2012


Hi all,

I am trying to run an lme4 model (logistic regression with mixed effects)
in MCMCglmm but am unsure how to implement it properly.

Currently, my lme4 model formula looks as follows: "outcome ~ (1 + var1 +
var2 | study) + var1 + var2"

In English, this means that I am fitting a random effects model, where the
intercept, var1 and var2 are jointly distributed according to study.

My question is now how I would translate this formula to the fixed and
random terms in MCMCglmm.

For the fixed part, I figured that I should make a variable
nooutcome=abs(1-outcome) because it can then be modeled with a
multinomial2 family as there is no binomial(logit) option available. 
Then, the fixed part would look as follows:

cbind(outcome,nooutcome)~1+var1+var2

However, I am unsure how to specify the random effects over the intercept,
var1 and var2 jointly. So far, I was able to generate the following:

random=~us(var1):study+us(var2):study+us(1):study

which I think corresponds to  "outcome ~ (1  | study) + (0+var1  | study) 
+ (0+var2  | study) +  var1 + var2" instead of "outcome ~ (1 + var1 + var2
| study) + var1 + var2"

I would appreciate any help.

Thomas



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