st: xtmixed question

[David Airey <david.airey@Vanderbilt.Edu>]

When I use a maximum likelihood mixed model with clusters that have  
unequal sizes, are the fixed effects modeled in a way that reflects  
this?

So in a model like,

xtmixed y treatment || group:

where multiple groups are each assigned to one of two treatments, but  
groups are different sizes, is this accounted for by these types of  
models?

So if I were to average the groups and use the summary statistics in  
a linear regression model, I might weight the analysis by cluster  
size, reducing influence of small clusters relative to large  
clusters. If I use xtmixed directly, should I worry about this?
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