Re: The effect of random interactions.
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Re: The effect of random interactions.

G'day all.

I'm currently analysing a two site chick pea trial with primary focus 
being fungicide application time in relation to yield.
The ranking of the five chick-pea varieties is also of importance.
The raw means of the five varieties are unusual as one variety yields 
quite poorly at the first site and exceptionally well in another, while 
all other varieties yeild relatively consistently.
The model Yield ~ mu c(site) !r site.VARIETY
produces effects in the solution file:
  site.VARIETY             1.BohatyrNZ      -0.3062      0.1959    
  site.VARIETY             1.Dundale         0.7861E-01  0.1959    
  site.VARIETY             1.Bluey           0.6107E-01  0.1959    
  site.VARIETY             1.Jupiter         0.2128E-01  0.1959    
  site.VARIETY             1.PSE23           0.1452      0.1959    
  site.VARIETY             2.BohatyrNZ       0.3062      0.1959    
  site.VARIETY             2.Dundale        -0.7861E-01  0.1959    
  site.VARIETY             2.Bluey          -0.6107E-01  0.1959    
  site.VARIETY             2.Jupiter        -0.2128E-01  0.1959    
  site.VARIETY             2.PSE23          -0.1452      0.1959    

This is clearly incorrect as each variety has an effect of the same 
magnitute, negated, at both sites. I'm wondering why these effects have 
been produced in this manner.
No error variance structure has been applied to this interaction term.

Fitting the model again with !r site.VARIETY replaced by
!r site|1/VARIETY site|2/VARIETY
produces the desired effects.

Cheers, Leighton.