[R] nested design; intercept

[Mark Difford]

 Dear R-help,

I am sorry if this is more of a stats question than an R-question, but I have found it difficult to get a clear answer by other means.

Q. Would it be "wrong" to specify a nested model and retain a common intercept, e.g.

lm(NH4 ~ Site/TideCode + 1)

I am aware (?) that my Site-coefficients are now calculated relative to my reference Site  (treatment.contrasts), *but* that my TideCode levels now relate to their reference level within Site.

Is that correct?

Thank you in advance for help.

Regards,
Mark Difford.

  
Mark Difford 
Ph.D. candidate, Botany Department, 
Nelson Mandela Metropolitan University, 
Port Elizabeth, SA.