BACKGROUND
When developing risk models for binary data with small or sparse data sets, the standard maximum likelihood estimation (MLE) based logistic regression faces several problems including biased or infinite estimate of the regression coefficient and frequent convergence failure of the likelihood due to separation. The problem of separation occurs… (More)

L1 and L2 penalized regression models. R Package version 0.9-47; 2016. Retrieved from http://CRAN.R-project.org/ package=penalized. Rahman and Sultana BMCMedical ResearchMethodology