[R-meta] [metafor package] Metaanalysis using lmer.

[Michael Dewey]

Dear Marcel

You seem to have a large number of grouping variables (the ones to the 
right of the | symbol) which means you have few observations within any 
given cell of your design. I think you either need more data or a 
simpler model.

Michael

On 02/07/2018 12:19, Marcel Lars Meyert wrote:
> Hello everyone,
> 
> Thank you so much for accepting me to this newsletter.
> 
> As I am fairly new to metaanalysis and especially metaanalysis with R, I
> have a question concering the usage of the lmer-command.
> 
> The Multilevelanalysis consists of first and second level variables.
> 
> The first level variable here is: Diff_comp and the second level
> variables: Lead_construct, Out_alpha, Meta_N, Pub_type, Country.
> 
> I want to use the lmer-command as following:
> 
> Test_analysis = lmer(yi ~ Diff_comp + (Diff_comp | Lead_construct) +
> (Diff_comp | Out_alpha) + (Diff_comp | Meta_N) + (Diff_comp | Pub_type)
> + (Diff_comp | Country), data = dat)
> 
> As a result I get following message:
> 
> Warning message:
> In optwrap(optimizer, devfun, getStart(start, rho$lower, rho$pp),  :
>    convergence code 1 from bobyqa: bobyqa -- maximum number of function
> evaluations exceeded
> 
> Additionally, if I print it, I get the following result:
> 
> Linear mixed model fit by REML ['lmerMod']
> Formula: yi ~ Out_Breuer + (Out_Breuer | Lead_construct) + (Out_Breuer |
>   
>      Out_alpha) + (Out_Breuer | Meta_N) + (Out_Breuer | Pub_type) +
> (Out_Breuer | Country)
>     Data: dat
> REML criterion at convergence: 103.1168
> Random effects:
>   Groups         Name        Std.Dev.  Corr
>   Meta_N         (Intercept) 0.000e+00
>                  Out_Breuer  6.178e-07  NaN
>   Out_alpha      (Intercept) 2.694e-03
>                  Out_Breuer  2.507e-02 -0.97
>   Pub_type       (Intercept) 3.535e-01
>                  Out_Breuer  9.909e-02 -1.00
>   Country        (Intercept) 2.835e-07
>                  Out_Breuer  1.066e-07 -1.00
>   Lead_construct (Intercept) 2.586e-01
>                  Out_Breuer  6.867e-02 -1.00
>   Residual                   3.100e-01
> Number of obs: 165, groups:  Meta_N, 41; Out_alpha, 31; Pub_type, 5;
> Country, 2; Lead_construct, 2
> Fixed Effects:
> (Intercept)   Out_Breuer
>     -0.45167      0.09203
> convergence code 1; 0 optimizer warnings; 0 lme4 warnings
> 
> My question: Why is the correlation almost always -1.00 ?. Did I use the
> command right ?. As I already wrote, I am fairly new to all this and
> just want to check, whether I am on the right path, before I present
> false results. If any more information is needed, please tell me and I
> will respond as soon as possible.
> Thank you so much in Advance.
> 
> Best Wishes
> Marcel Meyert
> 	[[alternative HTML version deleted]]
> 
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-- 
Michael
http://www.dewey.myzen.co.uk/home.html