What you think about the following:
 > set.seed(1)
 > DF0.3 <- data.frame(X=c("a","a", "b"),
y=rnorm(3))
 > lme(y~1, random=~1|X, data=DF0.3)
Linear mixed-effects model fit by REML
   Data: DF0.3
   Log-restricted-likelihood: -2.148692
   Fixed: y ~ 1
(Intercept)
  -0.4261464
Random effects:
  Formula: ~1 | X
          (Intercept)  Residual
StdDev: 1.280461e-06 0.5383504
Number of Observations: 3
Number of Groups: 2
 >
	  hope this helps.
	  spencer graves
p.s.  I confess I had difficulties parsing your question.  First, I had 
to Google for "HLM".  I figured it was NOT "Home Life
Ministries".
"Hierarchical Linear Models" seemed more consistent with the context. 
Second, I wasn't even sure about what you meant by "category".  I
assume
it's what is returned by the "levels" function when applied to a
"factor".
Robin Martin wrote:
> HLM question?
> 
>  
> 
> Is there a minmum number of observations required for a category..I have
> individusals in work teams.I have incomplete data for all the teams
> ..sometimes I only have data for one person in a team.I assume that HLM
> can't work here!  But what would be the mimimal.at the moment I have a
> sample of about 240 in about 100 teams with teamsizes form 2 to 5.
> 
>  
> 
> Any advice?
> 
>  
> 
> Thanks
> 
>  
> 
> Robin
> 
>  
> 
> _____________________________________________________________
> 
>  
> 
> Dr Robin Martin
> 
> School of Psychology
> 
> University of Queensland
> 
> Brisbane, QLD 4072
> 
> Australia
> 
>  
> 
> Level 1, Room 132, McElwain Bldg
> 
> tel. +61 7 3365 6392
> 
> fax. +61 7 3365 4466
> 
> email r.martin at psy.uq.edu.au
> 
> web-page http://www.psy.uq.edu.au/people/personal.html?id=275
> 
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