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groupdir
2017 Sep 29
0
Error in Lordif: slope is missing or negative
Hi all
I am not an experienced user of R.
I am trying to perform DIF analysis using Lordif and I get the follow error:
> GroupDIF <- lordif(resp.data=Resp, group=Group, criterion="R2", pseudo.R2="McFadden", R2.change=0.02)
Iteration: 500, Log-Lik: -137340.437, Max-Change: 0.00119
EM cycles terminated after 500 iterations.
(mirt) | Iteration: 1, 14 items flagged for DIF (22,25,34,60,64,71,73,75,81,82,83...