Difference between 3 RMark models

Hi all,
A friend of mine is starting to work with MARK and RMark and asked me the following question. I wasn't sure how to answer, so I'm posting it for him here:
"I am looking for a good explanation of the differences between the RMark models Robust, RDHet and RDFullHet? I know what the parameters are in each, I am just not sure how the different models estimate the different parameters.
I am getting "better" results from my data with RDHet, but I am not sure why, so hopefully a better understanding of the models will help."
Thanks in advance,
Serge
A friend of mine is starting to work with MARK and RMark and asked me the following question. I wasn't sure how to answer, so I'm posting it for him here:
"I am looking for a good explanation of the differences between the RMark models Robust, RDHet and RDFullHet? I know what the parameters are in each, I am just not sure how the different models estimate the different parameters.
I am getting "better" results from my data with RDHet, but I am not sure why, so hopefully a better understanding of the models will help."
Thanks in advance,
Serge