# Coxph interactions not working #15

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opened this Issue Jan 12, 2016 · 2 comments

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### lckarssen commented Jan 12, 2016

 This is a 'liftover' of bug #6194 in the R-forge tracker. Reported on ProbABEL v0.4.5. See forum post http://forum.genabel.org/viewtopic.php?f=10&t=975. From there: When our phenotype file includes four columns (ID, Age, Event, cov1) and the interaction parameter is specified as interaction==1, the model given is incorrect (Coxph model: ( Age , Event ) ~ mu + cov1 + SNP_A1 + mu*SNP_A1). When the interaction parameter is specified as interaction==2, the model shown is now correct, Coxph model: ( Age , Event ) ~ mu + cov1 + SNP_A1 + cov1*SNP_A1, but the analysis doesn't run, giving the following error error: Interaction parameter is out of range (interaction=2) When we include a phenotype file with an additional covariate column (ID, Age, Event, cov1, cov2) and specify interaction==2, the model looks ok (with the exception of a covariate we didn't want to include), Coxph model: ( Age , Event ) ~ mu + cov1 + cov2 + SNP_A1 + cov1*SNP_A1, and the analysis seems to run, but it's not clear what analysis is being run to give the results; we can't replicate any of the results shown in R.

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### lckarssen commented Apr 22, 2016

 I have just tested this on commit 4180862 and this bug is indeed present.

 Fix Issue #15: interactions in Cox broken 
This fixes the --interactions option when using pacoxph. With the
introduction of the (mathematically useless) \mu in the Cox model (which
was introduced to fix bug 1266 (pacoxph with no covariates) on R-forge,
https://r-forge.r-project.org/tracker/index.php?func=detail&aid=1266&group_id=505&atid=2058),
the extra parts of code where we adjusted for the missing \mu were
inadvertently kept. Cox + interactions must have been broken since then.
 ec4798f 

### lckarssen added a commit that referenced this issue Apr 22, 2016

 Merge pull request #26 from lckarssen/fix_issue15 
Fix issue #15
 6d23885 
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### lckarssen commented Apr 22, 2016

 Closed by PR #26.