split plot with RCBD multi-sites


New Member
I have some question concerning the statistical analysis of the data I hope you can inform me
I have a designed experiment RCBD in split plot with the factor nitogen (N) as main plot and the factor cropping system (CS) as slit plot
this experiment was carried out in three different site ( S1 / S2 / S3)
When I analyze each site alone I have no problem
I use the following model with the package 'agricolae'
For example for site 1 (S1)

But when i want to analyse the three sites together. I do not know how to put the site factor (S) knowing that I want to have the interractions S * N / S * CS / S * CS * N

Is the site factor must between random or fixed?

I'm wondering if you could quickly advise on the best statistical analysis for my data.

If you have any thoughts on any of these points, I would be glad to hear them.

Best regard
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