hi
     I've been using this code to set a reference level for uni and multivariate analysis
          rmix$interviewmethodcode<-relevel(mix$interviewmethodcode,ref="SAQ")
          summary(rma.1<-rma(yi,vi,mods=~interviewmethodcode,data=rmix,method="SJ",knha=F,weighted=F,intercept=T))
    giving this output:
          Model Results:
                              estimate      se     zval    pval    ci.lb   ci.ub
          intrcpt                     0.1437  0.0176   8.1485  <.0001   0.1091  0.1783  ***
          interviewmethodcodeACASI    0.0022  0.0412   0.0545  0.9566  -0.0784  0.0829
          interviewmethodcodeFTFI    -0.0926  0.0656  -1.4112  0.1582  -0.2213  0.0360

However, when i use the same code with a different variable (below) I get the error message -  "Error in qr.solve(wX, diag(k)) : singular matrix 'a' in solve".
         rmix$continent<-relevel(mix$continent,ref="North America")
         summary(rma.1<-rma(yi,vi,mods=~continent,data=rmix,method="SJ",knha=F,weighted=F,intercept=T))

Can anyone help to see where the problem is?
    thanks
    Branwen




hi
 I've been using this code to set a reference level for uni and multivariate analysis

      rmix$interviewmethodcode<-relevel(mix$interviewmethodcode,ref="SAQ")
      summary(rma.1<-rma(yi,vi,mods=~interviewmethodcode,data=rmix,method="SJ",knha=F,weighted=F,intercept=T))
giving this output:

      Model Results:

                          estimate      se     zval    pval    ci.lb   ci.ub
      intrcpt                     0.1437  0.0176   8.1485  <.0001   0.1091  0.1783  ***
      interviewmethodcodeACASI    0.0022  0.0412   0.0545  0.9566  -0.0784  0.0829
      interviewmethodcodeFTFI    -0.0926  0.0656  -1.4112  0.1582  -0.2213  0.0360

However, when i use the same code with a different variable (below) I get the error message -  "Error in qr.solve(wX, diag(k)) : singular matrix 'a' in solve".

     rmix$continent<-relevel(mix$continent,ref="North America")
     summary(rma.1<-rma(yi,vi,mods=~continent,data=rmix,method="SJ",knha=F,weighted=F,intercept=T))

Can anyone help to see where the problem is?
thanks
Branwen




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