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Published byCalista Herringshaw Modified over 10 years ago
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Julian Archer Shannon Cummings Ashley Green David Ong
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Introduction Problem Statement Initial Data One Queue Model Multiple Queue Model Overall Results Conclusion
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Sue of Sue’s Market has hired us a consultant firm to solve a number of issues that she has in her current store Goal: ◦ Reduce wait time for customers ◦ Create a schedule that allows for worker limitations ◦ Save Sue money while creating a checkout areas with maximum output and efficiency. ◦ Having the least amount of baggers and cashiers working at one time to maximum profit
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Staffing of employees during peak hours ◦ 2pm-10pm ◦ Employees can only work 3-5 hours a day Long lines ◦ Desired Queue Wait: Optimal: 2-3 minutes Acceptable: 10-12 minutes ◦ Desired Queue Length: 4-5 people Minimizing Cost
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After conducting a best fit analysis it was found that the number of items purchased per customer, on average, must be distributed empirically. MIN: 4 items MAX: 149 ITEMS Sample mean: 88.9 Number of Items Per Customer
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From this graph we observe that the customers arrive at a lognormal distribution with a logarithmic mean of 0.00983 and a logarithmic standard deviation of 0.00308. However, the p- value is less than 15% which tells us that we have to use the empirical distribution. Initial Data Interarrival Times (Monday-Thursday)
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Payment Methods
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Basic Flow ◦ Assign customers amount of shopping items ◦ Decides to determine customer movement Resource Usage ◦ Cashier Resources Seized with series of delays Based on schedule ◦ Bagger Resources Bagging process
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Initial Data Collection: Changing Resources ◦ Focused on: Number Out of System Total Runtime Queue Wait Times and Lengths Resource Utilization and Busy Cost [(runtime/60)*5.5*#Baggers]+[(runtime/60)*7.25*#Cashie rs] ◦ Goal to Reduce: Wait times and lengths Cost Runtime
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Optimal Result: 12 Cashiers & 4 Baggers
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Second Stage Data Collection ◦ Action: Changed Cashier Schedule Fixed Amount of Baggers (4) ◦ Main Focus Queue wait time and length Still looked at same parameters as earlier
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Optimum 8 Hour Cashier Schedule: Max = 15 Cashiers Min = 5 Cashiers
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Third Stage Data Collection ◦ Action: Keep optimized cashier schedule Vary bagger schedule ◦ Main Focus: Cost Wait time and length Same parameters
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Optimal 8 Hour Bagger Schedule: Max = 5 Baggers Min = 1 Bagger
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Final Stage of Data Collection ◦ Action: Vary cashier schedule beyond 8 hours Vary bagger schedule beyond 8 hours ◦ Main Focus Cost Queue Wait and Length Runtime Same previous parameters
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Optimal Cashier ScheduleOptimal Bagger Schedule
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Total Cost: $470.84 per day ◦ =((7.25*MR(Cashier)(TNOW/60)) + (5.50*MR(Bagger)(TNOW/60)) Total Average Queue Wait: 4.21 minutes ◦ Cashier Wait: 3.06 minutes ◦ Bagger Wait: 1.15 minutes Average Cashier Queue Length: ∽5 People Total Runtime: 556.66 minutes
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Single Entry Assign Attributes and Variables Decide Shopping Time Delay Decide 1 of 20 Counters Seize Cashier
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Decide Price Check Delays Decides for Payment Type based on number of Items Purchased Decided If Bagger available or not Release Resources Exit Sub model
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◦ Decide bagging type ◦ Decrement customers ◦ Dispose Customers from system
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Benefits of One Large Queue Benefits of Multiple Small Queues Equal customer wait times Avoid unnecessary time choosing a lane Provides for more orderly checkout process Allows for specialized lanes ◦ Express ◦ Self check out ◦ Special payment lanes More familiar Do not have to worry about queue placement
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Optimized Bagger and Cashier Schedules ◦ Adhered to 3-5 hour constraints ◦ Extended schedule beyond 8 hours to account for overtime Minimize Queue Time ◦ Preferred 2-3 Minutes, Max 10-12 Minutes Average of 6-7 Minutes ◦ Our Queue: 4.21 Minutes Minimize Queue Length ◦ Queue length less than 5 people Decreased Cost and Runtime ◦ Total Cost: $470.84 ◦ Total People In and Out of System: 891 People ◦ Total Runtime: 556.66 Minutes
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