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Sport Obermeyer. What to order? What are the issues?. A Sample Problem. Commit 10,000 units before show Commit 10,000 units after show Minimum of 600 units. A First Approach. Ignore differences in Profit margins Salvage values Ignore minimum lot sizes Consider only first order cycle.
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Sport Obermeyer • What to order? • What are the issues?
A Sample Problem • Commit 10,000 units before show • Commit 10,000 units after show • Minimum of 600 units
A First Approach • Ignore differences in • Profit margins • Salvage values • Ignore minimum lot sizes • Consider only first order cycle
Normal Distribution Std Dev.s
Idea 1 • Make all products equally likely to sell out • Choose a single std dev. To set production quotas for all products
Normal Distribution Set order Qty to this many std. devs Probability we stock out = Probability demand exceeds over qty = 0.86 Probability we discount last item = Probability demand is smaller than order quantity = 0.14 Std Dev.s
What’s Wrong with This? • What else should we be looking at? • Still just worried about • Order up to 10,000 • One order cycle • No minimum order qty.
A Second Idea • Look at 1 Product • How to trade off risks of overstock (discounting) vs risks of understock (lost sales)? • If we order Q • The last item faces what risk of being discounted? • Probability Demand < Q = F(Q) • The last item faces what risk of selling out • Probability Demand > Q = 1 - F(Q)
We want to be indifferent • We want two to be equal • Expected loss from Overstock = CO*F(Q) • Expected loss from Lost Sale = CL*(1-F(Q)) • A little Algebra: • F(Q) = CL/(CO+CL)
Example • Oversimplification • Lost Sale: CL = Selling Price - Cost • Discount: CO = Cost - Salvage Value • Electra: • Selling Price $173 • Cost $ 50 • Salvage $ 0 • Lost Sale: CL = $123 • Discount: CO = 50 • Want Probability of Discount = F(Q) = 123/173 = 0.71 • Find Q with this cumulative probability: ~2,599
Additional Thoughts • What’s the derivative of the cost as a function of order quantity? • Expected Cost of Discounting Last Item (increases with order size) - Expected Cost of Stocking Out (decreases with order size) • Decrease Order with largest estimated derivative
2-Rounds • What additional Issues? • What rules of thumb? • Only order late • Surely order early
Differences in Suppliers • Hong Kong • Higher Cost • Smaller Minimums • Faster • What rules of Thumb?