[R-sig-ME] Dropping correlations bet. random-effects in lme4 syntax

[Phillip Alday]

I have no idea what 0* means, but 0+ means "suppress the intercept"
(which has knock-on effects for categorical variables and whether
they're represented in the model as (nlevels-1) contrasts or nlevels).

For the other things: try it out. The output of summary(m1) will show
you which levels and correlations were kept.

On 03/10/2020 18:44, Simon Harmel wrote:
> Thanks Phillip. What would be the meaning of placing `0 +` next to any
> of the random effects (e.g., B) as shown in m2?
>
> m1 <- lmer(y ~ A * B * C + (A * C | group) + (B|group) , data = data)  
>
> m2 <- lmer(y ~ A * B * C + (A * 0+ B * C  | group), data = data)  
>
> On Sat, Oct 3, 2020 at 11:33 AM Phillip Alday <phillip.alday using mpi.nl
> <mailto:phillip.alday using mpi.nl>> wrote:
>
>     You can split the specification of your grouping to achieve this, at
>     least in part:
>
>     lmer(y ~ A * B * C + (A * C | group) + (B|group) , data = data)
>
>     Note that life gets tricky with the interaction terms.
>
>     Phillip
>
>     On 03/10/2020 06:35, Simon Harmel wrote:
>     > Hello all,
>     >
>     > I know to drop all correlations among all level-1 predictors in
>     the random
>     > part of an lmer() call, I can use `||`. But I was wondering how
>     to drop
>     > correlations (a) "individually" or (b) "in pairs"?
>     >
>     > Example of (a) is how to drop the correlation of B with others
>     (A & C)?
>     > Example of (b) is how to drop the correlation between B and C?
>     >
>     > lmer(y ~ A * B * C + (A * B * C  || group), data = data)
>     >
>     > Thanks,
>     > Simon
>     >
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>     >
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