Purpose: The Iron Triangle, also called the Triple Constraint, is a central concept to project management research and practice, representing the relationship between key performance criteria. However, there is disagreement about which criteria should be represented on the vertices of this...

Structured additive regression (STAR) models provide a flexible framework for modeling possible nonlinear effects of covariates: They contain the well established frameworks of generalized linear models (GLM) and generalized additive models (GAM) as special cases but also allow a wider class of...