[R] random sampling but with caveats!

2011-09-08 Thread Rebecca Ross
Hi, I wonder if someone can help me. I have built a gam model to predict the presence of cold water corals and am now trying to evaluate my model by splitting my dataset into training/test datasets. In an ideal world I would use the sample() function to randomly select rows of data for me so fo

[R] Specify contrasts in R

2010-08-02 Thread Rebecca Ross
problem using this contrast set-up in a mixed model? I am not sure how the 'block' effect would be interpreted for the mid-parent values, or indeed if it is sensible to include it as a random effect. Thank you in advance for your help, Rebecca Ross