مقایسهٔ روش‌ها

	مجموعه موارد گذشته‌نگر	مجموعه موارد - مطالعه مشاهده‌ای توصیفی
حوزه	اپیدمیولوژی	اپیدمیولوژی
خانواده	Process / pipeline	Process / pipeline
سال پیدایش	Long-standing practice; codified in EBM frameworks during 1990s–2000s	Longstanding; systematized in 20th century clinical research
پدیدآور	Clinical medicine tradition (no single originator); formalized in evidence-based medicine literature	Historical clinical practice; formalized in modern evidence-based medicine literature
نوع	Observational descriptive study design	Observational descriptive study
منبع بنیادین	Kooistra, B., Dijkman, B., Einhorn, T. A., & Bhandari, M. (2009). How to design a good case series. Journal of Bone and Joint Surgery, 91(Suppl 3), 21–26.	Case series. Wikipedia.
نام‌های دیگر	retrospective case series, chart review case series, historical case series, medical records case series	case series report, clinical case series, consecutive case series, patient series
مرتبط	4	5
خلاصه	A retrospective case series is an observational study that systematically describes the clinical features, treatments, and outcomes of a defined group of patients by examining pre-existing medical records or administrative data. It looks backward in time — data have already been recorded before the study begins. With no control group, no randomization, and no prospective follow-up, it sits near the base of the evidence hierarchy but remains one of the most practical and frequently published study designs in clinical medicine.	A case series is a descriptive observational study that documents the characteristics, clinical course, and outcomes of a group of patients who share a common condition, exposure, or intervention. Unlike case reports, which focus on a single patient, a case series aggregates data across multiple patients (typically three or more) to identify patterns, generate hypotheses, and characterize rare or novel conditions — without a concurrent control group.