100%(1)1 out of 1 people found this document helpful
This preview shows page 1 - 3 out of 3 pages.
Sources of Variability(For Service Operations)- Variability in Inter-Arrival Times (arrival rate)- Variability in Processing Times (service rate)High Variability + High Utilization = WIPTPTNat DeBeryDimensions of Service Quality– (Convenience, Reliability, Accuracy, Time, Responsiveness, Courtesy, Tangibles)Pull System= Demand impactswhen product is produced Push System= Demand does NOT impactwhen product is producedQuantifying Queues – Queues are inevitable because there will always be variability, it is important how you manage them - (μ) – Service Rate- Average number of customers that a service provider can serve per unit of time- (λ) – Arrival Rate- Average number of customers arriving per unit of time- (ρ) – Utilization Rate - If arrival rate < average service rate, Utilization Rate = Arrival Rate/Service Rate (ρ = λ/ μ)- If arrival rate > average service rate, utilization is > 100%Average # of Customers in System(L) = Arrival Rate/(Service Rate – Arrival Rate) &L = λ / (μ – λ)Average # Waiting in Line (Lq) = (Utilization Rate)*(Avg. # of Customer in System)&Lq = ρ LAverage Customer Time Spent in System(W) = 1 / (Service Rate – Arrival Rate) &W = 1/(μ- λ)Average Waiting Time (Wq) = Utilization Rate * Average Customer Time Spent in System &Wq = ρ WOptions to Improve System Performance –Reduce variability in demand!!!!!!- Inter-Arrival Times– Yield Management: incentivize smoothing of demandvia pricing/ promotion, scheduling system - Process Times – Schedule staff to meet peak loads, standardize work, modularize(clear task, repeated, no creativity) parallelize(different tasks done at the same time)- Addressing Process Cycle Times– Staff versatility to move the load- Uneven Utilization-Pool/flex resources by removing specialization. reduces work ‘lumpiness’: drives WIPTPTTask variety- Customer Values Process Speed – Consider teams to work on service requestManaging the “Gaps”- Interpretation Gap Not knowing the customer expectation- Design Gap –Wrong service quality standard- Development Gap – Service performance Gap- Promotion Gap –When promises don’t match deliveryIncrease in…OutputWaiting Customers (Inv.)Business Impact?Service RateUPDOWNPositiveArrival RateUPUPTrade-OffWaiting Room SizeUPUPTrade-OffVariabilityDOWNUPNegative# Of ServersUPDOWNPositive
SUPPLY CHAIN MANAGEMENT - Key problem in the supply chain is uncertaintyTruckload (TL) –Truckload of same packagesPer unit transport cost is lower than LTL. Higher holding cost.