Dear lme4 folk,

The lmer help page gives two examples:
(fm1 <- lmer(Reaction ~ Days + (Days|Subject), sleepstudy))
(fm2 <- lmer(Reaction ~ Days + (1|Subject) + (0+Days|Subject),  
sleepstudy))
How is the following different, in principle, from the above? Is it  
that the above treats (Intercept) and Days as orthogonal, whereas the  
latter checks to see if they are? What would be appropriate if the  
correlation between Days and Intercept (here 0.067, apparently) were  
large?
(fm3 <- lmer(Reaction ~ Days + (1 + Days | Subject), sleepstudy))
ЕЕЕЕЕ
Random effects:
Groups Name Variance Std.Dev. Corr
Subject (Intercept) 610.8 24.72
	Days 35.1 5.92 0.067
Residual 655.1 25.59
_____________________________
Professor Michael Kubovy
University of Virginia
Department of Psychology
USPS:     P.O.Box 400400    Charlottesville, VA 22904-4400
Parcels:    Room 102        Gilmer Hall
         McCormick Road    Charlottesville, VA 22903
Office:    B011    +1-434-982-4729
Lab:        B019    +1-434-982-4751
Fax:        +1-434-982-4766
WWW:    http://www.people.virginia.edu/~mk9y/



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