Hoping that @paul.buerkner or anyone else might be able to weigh in on whether it is (still?) possible to include monotonic spline terms in models fit with brms. I saw a thread from Jan '19 indicating that it is workable, though possibly involving some modifications to the scam pacakge. However, when I run the minimal working example posted on that thread (here) after modifying the scam source code as suggested, the resulting smooths are decidedly not monotonic. Of course, alternative suggestions for incorporating monotonic smooth of continuous covariates would be also welcome. Thanks!
# minimal example library(brms) library(scam) # N.B. this is compiled from source with modifications per referenced post b = brm(time ~ s(age, bs = "mpi"), data = kidney) marginal_smooths(b, spaghetti = T, nsamples = 10) # system info version _ platform x86_64-apple-darwin15.6.0 arch x86_64 os darwin15.6.0 system x86_64, darwin15.6.0 status major 3 minor 6.2 year 2019 month 12 day 12 svn rev 77560 language R version.string R version 3.6.2 (2019-12-12) nickname Dark and Stormy Night # brms version: 2.10.0