4. Model Selection and Evaluation# 4.1. Protocols for Quantification 4.1.1. Artificial-Prevalence Protocol (APP) 4.1.2. Natural-Prevalence Protocol (NPP) 4.1.3. Uniform Prevalence Protocol (UPP) 4.1.4. Personalized Prevalence Protocol (PPP) 4.2. Tuning Hyperparameters 4.3. References 4.4. Evaluation Metrics 4.4.1. Single Label Quantification (SLQ) Metrics 4.4.2. Regression-Based Quantification (RQ) Metrics 4.4.3. Ordinal Quantification (OQ) Metrics