เปรียบเทียบวิธี

	แบบจำลอง Erlang C	กฎของลิตเติล (L = λW)
สาขาวิชา	การวิจัยดำเนินงาน	การวิจัยดำเนินงาน
ตระกูล	Regression model	Regression model
ปีกำเนิด	1981	1961
ผู้ริเริ่ม	Agner Krarup Erlang; Cooper	John D. C. Little
ประเภท	Steady-state queueing model	Exact queueing identity
แหล่งต้นตำรับ	Cooper, R. B. (1981). Introduction to Queueing Theory (2nd ed.). North-Holland. ISBN: 978-0-444-00379-7	Little, J. D. C. (1961). A proof for the queuing formula: L = λW. Operations Research, 9(3), 383–387.
ชื่อเรียกอื่น	M/M/c Queue, Multi-Server Queueing Model, Erlang Delay Formula, Erlang-C Bekleme Modeli	L = λW Theorem, Little's Theorem, Little's Result, Little Yasası
ที่เกี่ยวข้อง	3	3
สรุป	The Erlang C model is a steady-state queueing formula that determines the probability a customer must wait before being served in a system with c parallel servers, Poisson arrivals at rate lambda, and exponentially distributed service times. Originally developed by Danish engineer Agner Krarup Erlang in the early twentieth century for telephone exchange design, and formalized in the queueing theory literature by Cooper (1981), it remains the canonical staffing model for call centers and service operations worldwide.	Little's Law is a fundamental theorem in queueing theory that relates the long-run average number of items in a stable system (L) to the long-run average arrival rate (λ) and the long-run average time an item spends in the system (W), expressed as L = λW. Introduced and rigorously proved by John D. C. Little in 1961, the law holds for virtually any stable stochastic system, requiring no assumptions about arrival distributions, service distributions, or queue disciplines.