What is all or none case series?

Answer 1

An "all or none" case series is a type of observational study design in which all subjects in the study either experience a particular outcome or none do, typically in response to a specific intervention or exposure. This approach is often used to assess the effectiveness of a treatment or intervention by providing clear evidence of its impact, as it eliminates ambiguity in outcomes. However, it may limit generalizability since it focuses on a specific population or condition. Such series are valuable for generating hypotheses but are not definitive for establishing causal relationships.