[R] Nested Designs

[Peter Dalgaard BSA]

"Alan T. Arnholt" <arnholt at math.appstate.edu> writes:

> > summary(aov(Strain~Machine + Head%in%Machine ))
>              Df Sum Sq Mean Sq F value  Pr(>F)  
> Machine       4  45.07   11.27  1.0532 0.38762  
> Machine:Head 15 282.87   18.86  1.7625 0.06252 .
> Residuals    60 642.00   10.70    
> 
> the F value to test "Machine" uses the MS residual 
> instead of MS Head(Machine).
> 
> When I use the following no F value is reported
> 
> > summary(aov(Strain~Machine + Head%in%Machine + Error(Machine)))
> 
> Error: Machine
>         Df Sum Sq Mean Sq
> Machine  4 45.075  11.269
> 
> Error: Within
>              Df Sum Sq Mean Sq F value  Pr(>F)  
> Machine:Head 15 282.88   18.86  1.7625 0.06252 .
> Residuals    60 642.00   10.70  
> 
> Is the second approach the best I can do?

Hmm. You're not giving us any data to try it on, but I think I'd have

aov(Strain~Machine + Error(Machine:Head))

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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