Undefined coefs

[tgerke]

fit_rr <- riskratio(death ~ stage + receptor, data = breastcancer)
summary(fit_rr)

The above block, found in both risks.Rmd and the help file for riskratio provides the following fit.

Coefficients: (3 not defined because of singularities)
               Estimate Std. Error z value Pr(>|z|)    
stageStage I     0.0000     0.0000     NaN      NaN    
stageStage II    0.8989     0.3875   2.320   0.0203 *  
stageStage III   1.8087     0.3783   4.781 1.75e-06 ***

The singularities warning may theoretically be expected, but could be confusing for users. A brief explanation of what's going on here could help; alternatively, we could think of ways to strip the warning from the summary() output if it is indeed the right thing.

[tgerke]

Same for the associated riskdiff calls.

[tgerke]

Still thinking out loud here: yes, of course this is the right answer, since the output is providing estimates for n parameters instead of n-1 for a factor. Let's think about how to set a reference term in the actual modeling functions.

[stopsack]

Great catch. Indeed, I think these apparent singularities arise because coefficients for variables that are not the exposure are not being calculated by marginal standardization approaches. Agree it would be good to get rid of the warning.