Introduction

In clinical medicine, drugs are usually administered to control some response variable within a specified range reflecting the patient’s disease state directly or indirectly. In most randomized controlled trials (RCTs) and randomized animal experiments, to evaluate the efficacy of a new treatment or the toxicity of a new treatment, the primary response variable on the same subject (e.g., a patient, an animal, a laboratory sample) is scheduled to be measured over a period of time, consisting of a baseline period before randomization, treatment period after randomization and, if necessary, a follow-up period after the end of treatment period. These subject-specific repeated measures or subjectspecific response profiles are analyzed for assessing difference in changes from baseline among treatment groups, leading to a treatment effect.