Dear Kristina
I do not use that package so cannot offer any direct help but
1 - can you fit the model with any other combination of parameters?
2 - what happens if you vary rho?
3 - if your data-set is small and not confidential can you share it,
otherwise can you show us str(anxiety_control) or
summary(anxiety_control) preferable without any variables you are not
using in this model?
4 - there is a robust option in Wolfgang Viechtbauer's metafor package
which might help although I am not sure how equivalent the analysis
approaches are.
On 01/09/2016 17:52, Kristina Loderer wrote:
Dear all,
I am trying to fit a simple (intercept-only) meta-analytic model using
the robumeta package using the following code:
anx_cont_mean<-robu(formula = es_fisher ~ 1, var.eff.size =
variance_fisher, studynum = study_ID, modelweights = "CORR", rho = 0.8,
small=TRUE, data = anxiety_control)
When I try to run this model, the following error message pops up:
Error in solve.default(sumXWX) :
system is computationally singular: reciprocal condition number = 0
What exactly does this mean in the context of meta-analysis? I haven't
been able to find any answers.
Thank you,
Kristina
-----------------------------------------
Kristina Loderer
Ludwig-Maximilians-Universität München
Department Psychologie
Leopoldstr. 13
D-80802 München
Telefon: +49 (89) 2180-6047
Email: kristina.lode...@psy.lmu.de
-----------------------------------------
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