2 Learning GoalsYield management (with protection levels) and overbooking give demand flexibility where supply flexibility is not possible.The Newsvendor model can be used:Single decision in the face of uncertainty.Underage and overage costs.
4 Some U.S. airline industry observations Since deregulation in 78, 137 carriers have filed for bankruptcy until 2006.From (the industry’s best 5 years ever) airlines earned 3.5 cents on each dollar of sales:The US average for all industries is around 6 cents.From the industry earned 1 cent per $ of sales.Carriers typicallyfill 72.4% of seats while thebreak-even load is 70.4%.- Utilization is about 3% higher inperhaps due to flight cancellations.Gas prices are high andwill remain so.Downsize airlinesMerge. Domestic/internationalAlternate transportation meansHigh speed train
5 Matching supply to demand when supply is fixed Examples of fixed supply:Travel industries (fixed number of seats, rooms, cars, etc).Advertising time (limited number of time slots).Telecommunications bandwidth.Size of the MBA program.Doctor’s availability for appointments.Revenue management is a solution:If adjusting supply is impossible – adjust the demand!Segment customers intoHigh willingness to payLow willingness to pay.Limit the number of tickets sold at a low price, i.e., control the average price by changing the mix of customers.
6 Environments suitable for revenue management The same unit of capacity (e.g., airline seat) can be used to deliver services to different customer segments (e.g., business and leisure customers) at different prices.High gross margins (so the variable cost of additional sales is low).Perishable capacity (it cannot be stored) and limited capacity (all possible customers cannot always be served).Capacity is sold in advance of demand: Costly adjustment of sold capacity.There is an opportunity to segment customers (so that different prices can be charged) and different segments are willing to pay different prices.It is not illegal or morally irresponsible to discriminate the customers.Is Revenue management for incoming MBA class possible?
7 Revenue Management: Booking limits and protection levels
8 The Park Hyatt Philadelphia 118 King/Queen rooms.Hyatt offers a rL= $159 (low fare) discount fare for a mid-week stay, targeting leisure travelers.Regular fare is rH= $225 (high fare) targeting business travelers.Demand for low fare rooms is abundant.Let D be uncertain demand for high fare rooms.Suppose D has Poisson distribution with mean 27.3.Assume most of the high fare (business) demand occurs only within a few days of the actual stay.Objective: Maximize expected revenues by controlling the number of low fare rooms sold.
9 Yield management decisions The booking limit is the number of rooms to sell in a fare class or lower.The protection level is the number of rooms you reserve for a fare class or higher.Let Q be the protection level for the high fare class. Q is in effect while selling low fare tickets.Since there are only two fare classes, the booking limit on the low fare class is118 – Q:You will sell no more than 118-Q low fare tickets because you are protecting (or reserving) Q seats for high fare passengers.118Sell no more than the lowfare booking limit, QQ seats protected forhigh fare passengers
10 The connection to the newsvendor A single decision is made before uncertain demand is realized.There is an overage cost:D: Demand for high fare class; Q: Protection level for high fare classIf D < Q then you protected too many rooms (you over protected) ...… so some rooms are empty which could have been sold to a low fare traveler.There is an underage cost:If D > Q then you protected too few rooms (you under protected) …… so some rooms could have been sold at the high fare instead of the low fare.Choose Q to balance the overage and underage costs.
11 Optimal protection level Overage cost:If D < Q we protected too many rooms and earn nothing on Q - D rooms.We could have sold those empty rooms at the low fare, so Co = rL.Underage cost:If D > Q we protected too few rooms.D – Q rooms could have been sold at the high fare but were sold instead at the low fare, so Cu = rH – rLOptimal high fare protection level:Optimal low fare booking limit = 118 – Q*Choosing the optimal high fare protection level is a Newsvendor problem with properly chosen underage and overage costs.
12 Hyatt example Critical ratio: Poisson distribution with mean 27.3 You can also use poisson(Q,mean=27.3,1)=0.29 Excel function to solve for Q.Answer: 24 rooms should be protected for high fare travelers. Similarly, a booking limit of = 94 rooms should be applied to low fare reservations.
13 Related performance measure calculations How many high-fare travelers will be refused a reservation?Expected lost sales = 4.10, From Table 13.2How many high-fare travelers will be accommodated?Expected sales = Expected demand - Lost sales = = 23.2How many seats will remain empty?Expected left over inventory = Q - Expected sales = = 0.8.What is the expected revenue assuming all low fare rooms are sold$225 x Exp. Sales(=23.2) + $159 x Booking limit(=118-24=94) = $20,166.Without yield management worst case scenario is selling all the rooms at the low fare and making $159 x 118 = $18,762.With revenue management revenue increases by (20,166-18,762)/18,762=7.5%
14 Example: Bulk Contracts Most consumers of production, warehousing, and transportation assets face the problem of constructing a portfolio of long-term bulk contracts and short-term spot market contractsLong-term contracts for low costShort-term contracts for flexibilityThe basic decision is the size of the bulk contractThe fundamental trade-off is between wasting a portion of the low-cost bulk contract and paying more for the asset on the spot market
15 Example: Bulk Contracts For the simple case where the spot market price is known but demand is uncertain, a formula can be usedcB = bulk ratecS = spot market priceQ* = optimal amount of the asset to be purchased in bulkOverage cost of buying too much in bulk: cB.Underage cost of buying too little in bulk: cS- cB.
16 Numerical Example for Bulk Contracts: Buying transportation capacity to bring goods from China Bulk contract cost = cB = $10,000 per million unitsSpot market cost = cS = $12,500 per million unitsNormal monthly Demand for transportation:m = 10 million units, s = 4 million unitsQ* = Norminv(( /12.5),10,4) million unitsThe manufacturer should sign a long-term bulk contract for Q* million units per month and purchase any transportation capacity beyond that on the spot market.
18 Ugly reality: cancellations and no-shows Approximately 50% of reservations get cancelled at some point in time.In many cases (car rentals, hotels, full fare airline passengers) there is no penalty for cancellations.Problem:the company may fail to fill the seat (room, car) if the passenger cancels at the very last minute or does not show up.Solution:sell more seats (rooms, cars) than capacity.Danger:some customers may have to be denied a seat even though they have a confirmed reservation.Passengers who get bumped off overbooked domestic flights to receiveUp-to $400 if arrive <= 2 hours after their original arrival timeUp-to $800 if arrive >= 2 hours after their original arrival timeAccording to April 16, 2008 decision of the Transportation Department
19 Hyatt’s ProblemThe forecast for the number of customers that do not show up( X ) is Poisson with mean 8.5.The cost of denying a room to the customer with a confirmed reservation is $350 in ill-will (loss of goodwill) and penalties.How many rooms (y) should be overbooked (sold in excess of capacity)?Newsvendor setup:Single decision when the number of no-shows in uncertain.Insufficient overbooking: Overbooking demand=X >y=Overbooked capacity.Excessive overbooking: Overbooking demand=X <y=Overbooked capacity.
20 Overbooking solution Underage cost when insufficient overbooking if X >y then we could have sold X-y more rooms…… to be conservative, we could have sold those rooms at the low fare, Cu = rL.Overage cost when excessive overbookingif X <y then we bumped y-X customers …… and incur an overage cost Co = $350 on each bumped customer.Optimal overbooking level:Critical ratio:
21 Optimal overbooking level Poisson distribution with mean 8.5Optimal number of overbooked rooms is y=7.Hyatt should allow up to reservations.There is about F(6)=25.62% chance that Hyatt will find itself turning down travelers with reservations.
23 Revenue management challenges … Demand forecasting.Wealth of information from reservation systems but there is seasonality, special events, changing fares and truncation of demand data.Dynamic decisions.Variable capacity:Different aircrafts, ability to move rental cars around.Group reservations; Cargo overbooking.How to construct good “fences” to differentiate among customers?One-way vs round-trip tickets.Saturday-night stay requirement.Non-refundability.Advanced purchase requirements.Multi-leg passengers/multi-day reservations for cars and hotels:
24 A solution to the multi-leg customer: buckets HeathrowO’HareJFKWith segment control there are only three booking limits for the O’Hare-JFK leg, one for each fare class.But an O’Hare-Heathrow customer may be more valuable, so you could have six booking limits, one for each fare-itinerary combination.But that leads to many booking limits, so group similar fare-itineraries into buckets:
25 Another solution to multi-legs: bid prices HeathrowO’HareJFKAssign a bid price to each segment:A fare is accepted if it exceeds the sum of the bid prices on the segments it uses:For example, an O’Hare-JFK fare is accepted if it exceeds $290A O’Hare-Heathrow fare is accepted if it exceeds $290+$170 = $460The trick is to choose good bid-prices.
26 SummaryYield management (with protection levels) and overbooking give demand flexibility where supply flexibility is not possible.The Newsvendor model can be used:Single decision in the face of uncertainty.Underage and overage costs.These are powerful tools to improve revenue:American Airlines estimated a benefit of $1.5B over 3 years.National Car Rental faced liquidation in 1993 but improved via yield management techniques.Delta Airlines credits yield management with $300M in additional revenue annually (about 2% of year 2000 revenue.)
27 Summary of the Course Modules 1. Flow analysis2. Formulations3. Queues4. Quality5. Inventory6. Revenue managementThe efficient transformation of inputs into outputs to suitably satisfy customers.
28 The End My teaching is over Your learning is forever Towards better Do not give up ever