Dear all,

I'd like to fit a model with random slopes without random intercepts. I
can't figure out the syntax and would appreciate some help.

Basically, I want to explore the full volume of parameter space for my
dataset. There's only one fixed effect, but several levels of random
variation. I can fit all combinations of random intercept and random slope
models as:

1) lmer( y ~ x + (1|A) ...)
2) lmer(y ~ x + (x|A) ...)


The logical way to remove the random intercept is to remove "A" from formula
2. But then lmer wouldn't know which level at which to fit the random
slopes. I tried "A-1" and "(A-1)" but both returned errors.

Thanks in advance.

Best wishes, Nick




PS I'd like to take this opportunity to add my voice to the chorus of
gratitude and enthusiasm about lme4. The old version of lmer was very slow
fitting random slope models and frequently returned convergence warnings,
probably due to my data structure (n=1200, very unbalanced). I've just
started using the newest lmer (aka lmer2) and am astonished to find a 40
fold increase in the speed of model fitting, and no warnings.


Nick Isaac
Zoological Society of London
nick.isaac@ioz.ac.uk
T: +44 (0) 20 7449 6670

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