SCM300 Exam 2 Study Guide.docx - SCM300 Exam 2 Study Guide...

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SCM300 Exam 2 Study GuideModule 05Goal of Waiting Line Management: Balance the cost paid by the customers (time) with the cost paid by the company (money paid to maintain the system). Parts of a Waiting Line System: A waiting line system is made up of three parts:Input Source:This is the population of people that might want service Waiting Line: The area in which customers wait for service.Service Facility:The area in which customers actually receive service 4 Managerial Considerations in Queuesa.Customers– How many are there? How quickly are they arriving?b.The Waiting Lines – What type of lines? How many lines?c.Employees – Who’s working in the system? How many? Skill level and Speed?d.Service Facilities – How effective and efficient is the process? Tools?Basic Waiting Line Terminology Queue:LineChannel:Line; here it often refers to the number of lines available at each stepPhase:A single step in a processInfinite Population of Customers:The number of possible customers that may come into the store is very high (or unlimited). When a customer enters the system, the odds of another entering the system are not impacted in any significant mannerFinite Population of Customers: The number of customers is limited Balking:When a potential customer sees the line but never joins the line because they think it looks too long and/or too slow.Reneging: When a customer joins the line, gets frustrated and leaves the line.Arrival (Lambda) rates: Define and Calculate Mean Arrival Rate: (λ). Number of customers arriving / unit of time. 15 customers per hourService (Mu) rates: Define and Calculate Mean Service Rate: (μ). Number of customers helped/unit of time. 24 customers/hourService Utilization Factor (Rho)Percentage of time worker is busy: (ρ). λ/μ15/24 = 0.625.Single-Server Formulas & Calculations (Simple Queuing Model)look at slidesArrival rates are guesses, some customer groups are small or large, well prepared or not, Service rates are guesses, does not account for reneging or balking.Multiple-Server Problems (Multiple Server Queuing Models)look at slides
Percentage of time each worker is busy, Probability the system is empty, Probability a customer will get served immediately, Customer number, Time, Service time.Trade-offs in managing waiting linesHaving too many staff and underutilizing them OR having long lines and angry customers. Both will lose money.Managerial decisions in queuing systemsThis doesn’t mean these formulas and the answers are useless. A smart manager can use the answers together with their knowledge of how waiting lines work and generate better solutions for managing the waiting line system. (look at single server formulas section).Customer behavior impacts on queuing systems Type of customers – prepared/unprepared, big/small orders, high/low maintenance.Arrival rates – steady stream? Buys and slow time periods? Seasonal trends?Finite vs Infinite populations Finite:Few potential customers. Every customer in the store significantly decreases the