Date:         Wed, 14 Nov 2007 16:04:20 -0500
Reply-To:     Sharif Aly <saly@UCDAVIS.EDU>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Sharif Aly <saly@UCDAVIS.EDU>
Subject:      SAS code for crossed random effects

Dear list,
Would anyone please explain to me how to indicate several random effects
crossed in a multilevel model?

My model has no fixed effects (other than intercept) and 4 random effects
levels: level 4 crossed with level 3 which in turn is crossed with level 2
which is nested in level 1?

Level 4:  farm
Level 3:  location (location is nested in farm)
Level 2:  time (time is crossed with location)
Level 1:  collector (collector is crossed with time)

My code (the last 2 lines were my attempt to imply the crossed factors):

proc mixed data=pcr;
class time farm collector location;
model pcr= /solution;
random intercept / subject= farm;
random intercept / subject=location (farm);
random intercept / subject= time (location farm);
repeated collector/ sub=time*location (farm) type=vc;



Best regards,
Sharif