Coordination by Option Contracts in a Retailer-Led Supply Chain with
Coordination by Option Contracts in a Retailer-Led Supply Chain with
Coordination by Option Contracts in a Retailer-Led Supply Chain with
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TSINGHUA SCIENCE AND TECHNOLOGY<br />
ISSN 1007-0214 22/22 pp570-580<br />
Volume 13, Number 4, August 2008<br />
<strong>Coord<strong>in</strong>ation</strong> <strong>by</strong> <strong>Option</strong> <strong>Contracts</strong> <strong>in</strong> a <strong>Retailer</strong>-<strong>Led</strong> <strong>Supply</strong> Cha<strong>in</strong><br />
<strong>with</strong> Demand Update *<br />
WANG Xiaolong (王小龙), LIU Liwen (刘丽文) **<br />
School of Economics and Management, Ts<strong>in</strong>ghua University, Beij<strong>in</strong>g 100084, Ch<strong>in</strong>a<br />
Abstract: This research exam<strong>in</strong>es how to use an option contract to coord<strong>in</strong>ate a retailer-led supply cha<strong>in</strong><br />
where the market <strong>in</strong>formation can be updated. Based on Stackelberg game theory, we build a mode <strong>with</strong> one<br />
supplier and one retailer <strong>in</strong> which the retailer designs contracts to coord<strong>in</strong>ate the supplier’s production <strong>in</strong> a<br />
two-mode production environment. This focuses on an option contract that consists of two option prices and<br />
one exercise price. By theoretical analysis and numerical example, we f<strong>in</strong>d that such a contract can coord<strong>in</strong>ate<br />
the supplier and retailer to act <strong>in</strong> the best <strong>in</strong>terest of the channel. The optimal pric<strong>in</strong>g conditions are<br />
given as follows: First, option prices should be negatively correlated to the exercise price and should be <strong>in</strong> a<br />
relevant range. Second, the first-period option price should be no greater than the second-period price and<br />
should be l<strong>in</strong>early correlated to the second-period option price when the latter is beyond some threshold. The<br />
results show that such option contracts can arbitrarily allocate the extra system profit between the two parties<br />
so that each party is <strong>in</strong> a w<strong>in</strong>-w<strong>in</strong> situation.<br />
Key words: supply cha<strong>in</strong> coord<strong>in</strong>ation; option contracts; retailer-led; demand update<br />
Introduction<br />
Contemporary bus<strong>in</strong>ess puts more and more emphasis<br />
on channels, shift<strong>in</strong>g power from supplier to retailer at<br />
the downstream end of a supply cha<strong>in</strong>, which is the<br />
closest to the customers. Mess<strong>in</strong>ger and Narasimhan [1] ,<br />
Ailawadi [2] , and Bloom and Perry [3] offer empirical<br />
evidence on how power has transferred <strong>in</strong> several <strong>in</strong>ternational<br />
retail<strong>in</strong>g markets. Such shift<strong>in</strong>g enables the<br />
retailers to lead the supply cha<strong>in</strong> <strong>in</strong> some sense. They<br />
then beg<strong>in</strong> to raise str<strong>in</strong>gent requirements on the suppliers’<br />
production, compared <strong>with</strong> the traditional case<br />
where the supplier dom<strong>in</strong>ates the supply cha<strong>in</strong> and coord<strong>in</strong>ates<br />
the retailer’s order<strong>in</strong>g behavior. Another<br />
Received: 2006-10-24<br />
* Supported <strong>by</strong> the National Natural Science Foundation of Ch<strong>in</strong>a<br />
(Nos. 70532004 and 70621061)<br />
** To whom correspondence should be addressed.<br />
E-mail: liulw@sem.ts<strong>in</strong>ghua.edu.cn<br />
Tel: 86-10-62783553; Fax: 86-10-62785876<br />
aspect is that the market situation often changes greatly<br />
long after the retailer has set an order. Some retailers,<br />
like Wal-Mart, deal <strong>with</strong> such problems <strong>by</strong> order<strong>in</strong>g<br />
less but more frequently. However, this volatile market<br />
puts great pressure on the suppliers who must make<br />
wise production/capacity build<strong>in</strong>g decisions to cope<br />
<strong>with</strong> the irregular orders which mirror a volatile market.<br />
Unfortunately, quite often suppliers fail to do that. In<br />
an effort to reduce mismatches between supply and<br />
demand, many <strong>in</strong>dustries, like the fashion <strong>in</strong>dustry (as<br />
reported <strong>by</strong> Fisher et al. [4] ) and the consumer electronics<br />
<strong>in</strong>dustry, are mov<strong>in</strong>g to tighten coord<strong>in</strong>ation across<br />
their supply cha<strong>in</strong>s. One important <strong>in</strong>itiative for suppliers<br />
is to develop faster, but typically more expensive,<br />
production modes that are capable of produc<strong>in</strong>g a second<br />
run of products closer to the sell<strong>in</strong>g season. This<br />
mode allows both sides to take advantage of updated<br />
demand forecasts. Also, the retailer can better manipulate<br />
the supplier’s production so that channel coord<strong>in</strong>ation<br />
is reached. This phenomenon has become more
WANG Xiaolong (王小龙) et al:<strong>Coord<strong>in</strong>ation</strong> <strong>by</strong> <strong>Option</strong> <strong>Contracts</strong> <strong>in</strong> a <strong>Retailer</strong>-<strong>Led</strong> …<br />
common <strong>with</strong> advances <strong>in</strong> computer-based manufactur<strong>in</strong>g<br />
technologies which significantly reduce production<br />
run times and product changeover times.<br />
However, the addition of another production mode<br />
is not enough to reach channel coord<strong>in</strong>ation due to<br />
double marg<strong>in</strong>alization which refers to the fact that a<br />
party’s relative cost structure becomes distorted when<br />
a transfer price is <strong>in</strong>troduced <strong>with</strong><strong>in</strong> a supply channel.<br />
For example, <strong>in</strong>troduc<strong>in</strong>g a wholesale price <strong>in</strong>to a s<strong>in</strong>gle-stage<br />
newsvendor model causes the ratio of the<br />
buyer’s underage and overage costs to fall short of the<br />
channel ratio. As a result, the buyer orders less than the<br />
channel optimal quantity. In a two-stage production<br />
environment, double marg<strong>in</strong>alization threatens to impact<br />
not only the total production quantity but also<br />
proper allocation of production between periods. The<br />
double marg<strong>in</strong>alization concept was first <strong>in</strong>troduced <strong>in</strong><br />
the economics literature <strong>by</strong> Spengler [5] , who raised the<br />
issue <strong>in</strong> terms of <strong>in</strong>appropriate prices rather than <strong>in</strong>appropriate<br />
quantities. Tirole [6] provided further details<br />
on the phenomenon. Many works <strong>in</strong> the operations<br />
management field, like those of Lariviere and<br />
Porteus [7] , have shown that price-only contracts generally<br />
fail to coord<strong>in</strong>ate the supply cha<strong>in</strong> due to double<br />
marg<strong>in</strong>alization. However, other contracts have proven<br />
to efficiently coord<strong>in</strong>ate the supply cha<strong>in</strong>. These contracts<br />
<strong>in</strong>clude buyback contracts [8] , revenue shar<strong>in</strong>g<br />
contracts [9] , sales rebate contracts [10] , quantity discount<br />
contracts [11] , and quantity flexibility contracts [12] .<br />
The goal of this paper is to provide guidance <strong>in</strong> design<strong>in</strong>g<br />
an option contract <strong>in</strong> a retailer-led supply cha<strong>in</strong>,<br />
<strong>in</strong> which the supplier’s production needs coord<strong>in</strong>ate<br />
<strong>with</strong> the existence of a market demand <strong>in</strong>formation<br />
update. The researches on option contracts <strong>in</strong> supply<br />
cha<strong>in</strong> management are ma<strong>in</strong>ly divided <strong>in</strong>to economic<br />
and operational areas. Typical economic works <strong>in</strong>clude<br />
Newbery [13] and Wu et al. [14] Typical operational<br />
works <strong>in</strong>clude Donohue [15] and Barnes-Schuster et<br />
al. [16] Our contract pric<strong>in</strong>g scheme builds most closely<br />
upon the work of Barnes-Schuster et al. [16] , which considers<br />
a comb<strong>in</strong>ation of committed orders and options.<br />
Barnes-Schuster et al. [16] analyze a two-period model<br />
<strong>with</strong> correlated demand. The present analysis studies a<br />
two-period model <strong>with</strong> demand <strong>in</strong>formation update <strong>in</strong><br />
which the market demand does not realize until the end<br />
of the second period.<br />
Specifically, consider one supplier and one retailer.<br />
571<br />
At the beg<strong>in</strong>n<strong>in</strong>g of the first period both parties anticipate<br />
a demand <strong>in</strong>formation update that will appear at<br />
the beg<strong>in</strong>n<strong>in</strong>g of the second period and they take this<br />
<strong>in</strong>to account <strong>in</strong> their first-period decisions. The coor-<br />
d<strong>in</strong>at<strong>in</strong>g contract is designed as follows: The option<br />
contract has three parameters for two option prices 1 o<br />
and o 2 and one exercise price e. The option prices<br />
serve as the unit compensation for the supplier’s production<br />
quantities. When the realized demand is beyond<br />
the retailer’s total order, the retailer will purchase<br />
the supplier’s excess <strong>in</strong>ventory, if any, to meet the<br />
market demand at the unit price e. With this contract,<br />
the retailer’s decision is to determ<strong>in</strong>e orders at the beg<strong>in</strong>n<strong>in</strong>g<br />
of each period and the supplier’s decision is to<br />
determ<strong>in</strong>e the production allocation between the two<br />
periods. This project aims to f<strong>in</strong>d an optimal set of<br />
contracts to coord<strong>in</strong>ate the channel and to realize a<br />
proper profit allocation.<br />
1 Two-Period Model<br />
The two-period model depicts the dynamics of a retailer<br />
who purchases from one ma<strong>in</strong> supplier and markets<br />
these products to a number of retail outlets, resell<strong>in</strong>g<br />
at retail price p for a s<strong>in</strong>gle sell<strong>in</strong>g season.<br />
Unlike traditional coord<strong>in</strong>ation models, the retailer <strong>in</strong><br />
the model leads the supply cha<strong>in</strong> and designs a proper<br />
contract to coord<strong>in</strong>ate the supplier’s production quantities.<br />
The specific contract form will be <strong>in</strong>vestigated.<br />
The retailer utilizes two periods of demand <strong>in</strong>formation<br />
to determ<strong>in</strong>e the order quantities. Dur<strong>in</strong>g the first period,<br />
the demand prediction is relatively less accurate<br />
<strong>with</strong> a distribution function denoted as F(D). At the<br />
beg<strong>in</strong>n<strong>in</strong>g of the second period (market demand not yet<br />
realized), more current market <strong>in</strong>formation is available<br />
which helps the retailer f<strong>in</strong>e-tune the forecast where an<br />
effective market signal will be observed depend<strong>in</strong>g on<br />
specific <strong>in</strong>dustry situations and the lengths of the two<br />
periods which may not necessarily be equal. This updated<br />
<strong>in</strong>formation is the market signal ε. Let G(·) denote<br />
its estimated cumulative distribution function and<br />
let F(·|ε) denote the demand distribution function conditional<br />
on the market signal. Assume that ε is expressed<br />
<strong>in</strong> the same units as the total demand and is<br />
also non-negative. Market demand is stochastically<br />
<strong>in</strong>creas<strong>in</strong>g <strong>in</strong> the market signal, i.e., given x, F( x| ε h ) <<br />
F( x| ε l ) for all ε h > εl<br />
(ε h and ε l are two arbitrary
572<br />
market signals). Assume that all distributions are cont<strong>in</strong>uous,<br />
<strong>in</strong>vertible, doubly differentiable, and <strong>in</strong>dependent<br />
of the wholesale and retail prices. Furthermore,<br />
they are all common knowledge to both parties from<br />
the beg<strong>in</strong>n<strong>in</strong>g of period 1.<br />
At the beg<strong>in</strong>n<strong>in</strong>g of period 1, the retailer orders 1 d<br />
units at a unit wholesale price w 1 based on a rough<br />
knowledge of the demand distribution. Once ε is<br />
observed, the retailer will adjust the order quantities <strong>by</strong><br />
order<strong>in</strong>g another d2 units at a higher unit wholesale<br />
price w 2 . Note that the retailer’s second order is cont<strong>in</strong>gent<br />
on the specific market signal. If the signal exhibits<br />
a rather weak demand <strong>in</strong> the future, the retailer<br />
will not set another order, i.e., d 2 = 0 .<br />
The supplier produces over two time periods <strong>in</strong> response<br />
to the retailer’s orders, <strong>with</strong> orders filled <strong>in</strong> one<br />
shipment before the sell<strong>in</strong>g season beg<strong>in</strong>s. The supplier<br />
has two different production modes. One is the cheap<br />
mode which <strong>in</strong>curs a unit production cost c 1 , and the<br />
other is the expensive mode which <strong>in</strong>curs a unit production<br />
cost c2 > c1.<br />
Assume that production costs<br />
<strong>in</strong>clude the cost of hold<strong>in</strong>g <strong>in</strong>ventory until delivery and<br />
the cost of delivery itself. Other cost parameters <strong>in</strong>clude<br />
a shortage penalty s paid <strong>by</strong> the retailer to the<br />
customers for each unit of unfilled demand, and a salvage<br />
value v received for each unit of <strong>in</strong>ventory rema<strong>in</strong><strong>in</strong>g<br />
at the end of the season no matter to which<br />
side it belongs. Suppose that all these prices and costs<br />
are exogenous and the analysis is limited to the most<br />
relevant and <strong>in</strong>terest<strong>in</strong>g case where p > w2 > w1 > c2<br />
><br />
c1 > v.<br />
Next assume that the lead time for the cheap<br />
mode (and the tim<strong>in</strong>g of the market signal) is such that,<br />
to ensure completion before the start of the sell<strong>in</strong>g<br />
season, the supplier must beg<strong>in</strong> production before observ<strong>in</strong>g<br />
the market signal. In contrast, the lead time for<br />
the expensive mode is short enough to allow production<br />
after the market signal is observed. Therefore, the<br />
supplier’s problem is to allocate production quantities<br />
between the two modes. Dur<strong>in</strong>g the first period, the<br />
supplier needs to determ<strong>in</strong>e how many products, denoted<br />
as q 1 , would be produced among the cheap<br />
mode. In the second period after a market signal is ob-<br />
served, the supplier has to determ<strong>in</strong>e how many products,<br />
denoted as q 2 , will be produced among the expensive<br />
mode, if necessary. Denote d = d1+ d2<br />
and<br />
Ts<strong>in</strong>ghua Science and Technology, August 2008, 13(4): 570-580<br />
q= q1+ q2.<br />
1.1 Centralized system performance:<br />
A benchmark<br />
To provide a benchmark, first consider the problem<br />
where the supplier and the retailer are each owned <strong>by</strong> a<br />
risk-neutral entity. The owner aims to maximize his<br />
own expected profit <strong>by</strong> choos<strong>in</strong>g first and second period<br />
production quantities ( q1, q 2)<br />
which solve the<br />
follow<strong>in</strong>g two-period optimization problem.<br />
∞<br />
c c<br />
max Π ( q1) =− cq 1 1+∫Π ( ε, q1, q2)d G(<br />
ε)<br />
(1)<br />
q10<br />
0<br />
c c<br />
where Π ( ε, q1, q2) = max π ( ε,<br />
q1, q2)<br />
and<br />
q20<br />
c<br />
π ( ε , q , q ) = − c q + pEm<strong>in</strong>{ D, q + q } + v( q + q −<br />
1 2 2 2 1 2 1 2<br />
Em<strong>in</strong>{ D, q1+ q2}) −sE[ D− m<strong>in</strong>{ D, q1+ q2}]<br />
(2)<br />
c<br />
Here, Π ( ε , q1, q2)<br />
represents the second-stage<br />
problem after the market signal is observed and the<br />
demand forecast is updated accord<strong>in</strong>gly. To express<br />
the second-stage problem <strong>in</strong>dependently of q 1 , substitute<br />
q for q1+ q2<br />
and rearrange the terms. This<br />
new formulation yields the same objective solution as<br />
the problem <strong>in</strong> Eq. (1).<br />
∞<br />
c c<br />
max Π ( q1) = ( c2 − c1) q1+∫Π ( ε, q1)d G(<br />
ε)<br />
(3)<br />
q10<br />
0<br />
c c<br />
where Π ( ε, q1) = max π ( ε,<br />
q)<br />
and<br />
qq c<br />
π ε 2<br />
ε<br />
0<br />
1<br />
q<br />
( , q) = ( p− c + s) q−( p− v+ s) F( x| )dx−sED<br />
(4)<br />
Note that given q 1 , the owner faces a newsvendor<br />
problem <strong>in</strong> period 2 but <strong>with</strong> an <strong>in</strong>itial <strong>in</strong>ventory and<br />
c c<br />
an adjusted demand distribution. Let ( q1, q ) denote<br />
the optimal solution to the central problem. The solution<br />
structure is given <strong>by</strong> Lemma 1.<br />
Lemma 1 The argument of the central first period<br />
c<br />
problem, Π ( q1)<br />
, is concave <strong>in</strong> the <strong>in</strong>itial production<br />
quantity q 1 . The optimal total production quantity is<br />
c c<br />
⎧q1,<br />
if ε ε(<br />
q1);<br />
c ⎪<br />
q = ⎨ −1<br />
⎛ p− c2+ s ⎞<br />
⎪F<br />
⎜ ε ⎟,<br />
otherwise,<br />
⎩ ⎝ p− v+ s ⎠<br />
c ⎧ c p− c2+ s⎫<br />
where ε ( q1) = sup ⎨ε : F( q1<br />
| ε)<br />
⎬ and the<br />
⎩ p− v+ s ⎭<br />
first-period optimal production quantity is implied <strong>by</strong><br />
c<br />
ε ( q1<br />
)<br />
c<br />
2 1 ∫ 0<br />
2 1<br />
c − c + [ p− c + s−( p− v+ s) F( q | ε)]d G(<br />
ε)<br />
= 0.<br />
∫
WANG Xiaolong (王小龙) et al:<strong>Coord<strong>in</strong>ation</strong> <strong>by</strong> <strong>Option</strong> <strong>Contracts</strong> <strong>in</strong> a <strong>Retailer</strong>-<strong>Led</strong> …<br />
c<br />
Proof First, prove the concavity of Π ( q1)<br />
. This<br />
c c<br />
only needs to prove that Π ( ε, q1) = max π ( ε,<br />
q)<br />
is<br />
qq1 concave <strong>in</strong> q 1 .<br />
Note that<br />
c * *<br />
⎧⎪ π ( ε,<br />
q ), if q c<br />
1 q ;<br />
Π ( ε,<br />
q1)<br />
= ⎨ c<br />
⎪⎩ π ( ε,<br />
q1),<br />
otherwise,<br />
*<br />
c c<br />
where q maximizes π ( ε , q).<br />
Now π ( ε , q)<br />
is obvi-<br />
2 c<br />
∂ π ( ε,<br />
q)<br />
ously concave <strong>in</strong> q because =−( p− v+ s)<br />
⋅<br />
2<br />
∂q<br />
c<br />
f( q| ε ) 0. Therefore, Π ( q1)<br />
is also concave <strong>in</strong> q 1 .<br />
The optimal total production quantity follows immediately<br />
from the fact that the second-period problem<br />
is a simple newsvendor problem <strong>with</strong> <strong>in</strong>itial <strong>in</strong>ventory<br />
q 1.<br />
Intuitively this quantity is positively related to the<br />
market signal. When the signal is not strong enough,<br />
the central planner will not produce a second sum. This<br />
idea is exhibited <strong>in</strong> Lemma 1 <strong>with</strong> a threshold value for<br />
c ⎧ c p− c2+ s<br />
the market signal: ε ( q1 ) = sup<br />
⎫<br />
⎨ε : Fq ( 1 | ε ) ⎬ .<br />
⎩<br />
p− v+ s ⎭<br />
This is the strongest signal that will still result <strong>in</strong> no<br />
second-period production. With this notation, suppose<br />
that the central planner’s expected profit is maximized<br />
at q , and then rewrite the problem as<br />
c<br />
1<br />
c c<br />
1 2 1<br />
c<br />
1<br />
c<br />
ε ( q1<br />
)<br />
∫ 0<br />
c c<br />
1<br />
∞<br />
c c<br />
∫ π ( ε, q )d G(<br />
ε),<br />
c<br />
ε ( q1<br />
)<br />
Π ( q ) = ( c − c ) q + π ( ε, q )d G(<br />
ε)<br />
+<br />
c 1 p c2 s<br />
where q F<br />
p v s ε<br />
− ⎛ − + ⎞<br />
= ⎜ ⎟ . Because<br />
⎝ − + ⎠<br />
c<br />
Π ( q1)<br />
is<br />
concave <strong>in</strong> q 1 , the first order condition works, i.e., an<br />
optimal first-period production quantity is implied <strong>by</strong><br />
c<br />
ε ( q1<br />
)<br />
c<br />
2 1<br />
0<br />
2 1<br />
∫<br />
c − c + [ p− c + s−( p− v+ s) F( q | ε)]d G(<br />
ε)<br />
= 0.<br />
□<br />
c<br />
Lemma 1 <strong>in</strong>troduces the concept of ε ( q1<br />
) which<br />
partitions the market signals <strong>in</strong>to two sets. If<br />
c<br />
ε ε(<br />
q1<br />
) , then the second-period production is not<br />
necessarily positive. Otherwise, it is exactly positive.<br />
1.2 Decentralized system performance <strong>with</strong>out<br />
coord<strong>in</strong>ation<br />
Here model the decentralized system as a Stackelberg<br />
game. The retailer sets orders <strong>in</strong> each period as mentioned<br />
above. The supplier <strong>in</strong> turn arranges production<br />
573<br />
based on the orders.<br />
Let d i denote the retailer’s order <strong>in</strong> period i. The<br />
problem is to choose d 1 and d2 = d − d1<br />
to maximize<br />
the expected profit. The problem structure is analogous<br />
to that <strong>in</strong> the centralized system.<br />
∞<br />
max ΠR( d1) =− wd 1 1+∫ ΠR( ε, d1, d2) d G(<br />
ε),<br />
d10<br />
0<br />
where ΠR( ε, d1, d2) = max πR( ε,<br />
d1, d2)<br />
and<br />
d20<br />
πR( ε , d1, d2) = − w2d2 + pEm<strong>in</strong>{ D, d1+ d2}<br />
+<br />
vd ( 1+ d2 − Em<strong>in</strong>{ Dd , 1+ d2})<br />
−<br />
sE[ D − m<strong>in</strong>{ D, d + d }].<br />
Rearrang<strong>in</strong>g,<br />
1 2<br />
max ΠR( d1) = ( w2 − w1) d1+∫ΠR( ε, d1) d G(<br />
ε)<br />
d10<br />
0<br />
where ΠR( ε, d1) = max πR( ε,<br />
d)<br />
and<br />
<br />
R 2<br />
d d1<br />
π ( ε, d) = ( p− w + s) d−( p− v+ s) F( x| ε)d<br />
x−sED. * *<br />
Let ( d1, d ) denote the optimal solution to the retailer’s<br />
problem. The solution structure is given <strong>in</strong><br />
Lemma 2.<br />
Lemma 2 The argument of the retailer’s first period<br />
problem, Π R( d1)<br />
, is concave <strong>in</strong> the <strong>in</strong>itial order<br />
quantity d 1 . The optimal total order is<br />
* *<br />
⎧d1,<br />
if ε ε(<br />
d1);<br />
* ⎪<br />
d = ⎨ −1<br />
⎛ p− w2+ s ⎞<br />
⎪F<br />
⎜ ε ⎟,<br />
otherwise,<br />
⎩ ⎝ p− v+ s ⎠<br />
where<br />
* ⎧ * p− w2+ s⎫<br />
ε( d1) = sup ⎨ε : F( d1<br />
| ε)<br />
⎬ and the first-<br />
⎩ p− v+ s ⎭<br />
period optimal order quantity is implied <strong>by</strong><br />
*<br />
ε ( d1<br />
)<br />
*<br />
2 1<br />
0<br />
2 1<br />
∫ <br />
w − w + [ p− w + s−( p− v+ s) F( d | ε)]d G(<br />
ε)<br />
= 0.<br />
The proof is quite similar to that of Lemma 1. Here,<br />
*<br />
ε ( d1<br />
) also partitions the market signals <strong>in</strong>to two sets.<br />
*<br />
If ε ε(<br />
d1<br />
) , then the retailer will not set a second<br />
order. Note the differences from the notations def<strong>in</strong>ed<br />
<strong>in</strong> Section 1.1. Furthermore, for a given x, ε ( x) < ε ( x)<br />
,<br />
which co<strong>in</strong>cides <strong>with</strong> the phenomenon that double<br />
marg<strong>in</strong>alization makes the buyer conservative. Compared<br />
<strong>with</strong> the central planner, given the same <strong>in</strong>ventory<br />
level, the buyer <strong>in</strong> the decentralized system needs<br />
a stronger market signal, which <strong>in</strong>duces a more<br />
optimistic demand estimate, to build up to that level.<br />
The supplier’s problem is to choose production<br />
∞<br />
∫<br />
0<br />
d
574<br />
quantities ( q1, q 2)<br />
that maximize his own expected<br />
profit, subject to the retailer’s order<strong>in</strong>g behavior. His<br />
decision on the second-stage production is relatively<br />
straightforward, i.e.,<br />
* * *<br />
q2 = max{ d − q1,0}<br />
.<br />
The difficulty lies <strong>in</strong> his decision on q 1 . Obviously<br />
he should at least produce d 1 , but should he produce<br />
more? The answer depends on his estimate on the likelihood<br />
of the retailer’s second order. For such a decision<br />
his problem is<br />
ε ( d1)<br />
max Π ( q ) = wd − cq + v( q − d )d G(<br />
ε)<br />
+<br />
q1d1 S 1 1 1 1 1<br />
0<br />
1 1<br />
ε ( q1<br />
)<br />
∫ ε ( d1)<br />
∞<br />
wd 2 2 vq1 d G<br />
∫<br />
ε ( q1<br />
)<br />
∫<br />
[ + ( − )]d ( ε ) +<br />
[ wd −c( d−q)]d G(<br />
ε ).<br />
2 2 2 1<br />
The solution to this problem is given <strong>by</strong> Lemma 3.<br />
Lemma 3 Given the retailer’s order<strong>in</strong>g behavior,<br />
the supplier will maximize his expected profit <strong>by</strong><br />
sett<strong>in</strong>g<br />
* *<br />
q1 d1 q′ 1<br />
* * *<br />
= max{ , } and q2 = max{ d − q1,0},<br />
where 1 q′ is implied <strong>by</strong> c2 − c1<br />
G( ε ( q′<br />
1))<br />
= .<br />
c2−v Because this problem has a newsvendor structure,<br />
the first order condition works. The proof is straightforward<br />
so the details are omitted. These problems<br />
have reviewed the benchmark and decentralized uncoord<strong>in</strong>ated<br />
system performance. Although the precise<br />
relationships between * *<br />
d 1 , q 1,<br />
and c<br />
q 1 depend<strong>in</strong>g on<br />
factors like the ratio of the two production costs, the<br />
ratio of the two wholesale prices, and the estimate of<br />
the market signal cannot be determ<strong>in</strong>ed, the channel is<br />
certa<strong>in</strong>ly not coord<strong>in</strong>ated. This is implied <strong>by</strong> Lemma 2<br />
which states that for a given market signal the retailer’s<br />
total order quantity is less than the optimal total <strong>in</strong>ventory<br />
required <strong>in</strong> a centralized system. The next section<br />
focuses on how an option mechanism coord<strong>in</strong>ates<br />
the supply cha<strong>in</strong> and realizes profit allocation.<br />
2 Channel <strong>Coord<strong>in</strong>ation</strong><br />
To coord<strong>in</strong>ate the channel, the retailer must choose the<br />
proper contract parameters so that the supplier’s production<br />
quantities <strong>in</strong> each period are equal to the opti-<br />
* c<br />
mal solutions <strong>in</strong> the centralized system, i.e., q = q<br />
and<br />
1 1<br />
* c<br />
q = q . To do so the retailer must give <strong>in</strong>centives<br />
Ts<strong>in</strong>ghua Science and Technology, August 2008, 13(4): 570-580<br />
to the supplier to overproduce <strong>in</strong> each period. Recall<br />
that q1d1 and q2 max{ d − q1,0}<br />
. Thus d 1 and<br />
max{ d − q1,0}<br />
are the m<strong>in</strong>imum production number<br />
for the supplier’s production <strong>in</strong> each period. The coord<strong>in</strong>at<strong>in</strong>g<br />
contract is def<strong>in</strong>ed as follows: The option contract<br />
has three parameters of two option prices o 1 and<br />
o 2 and one exercise price e . The option prices are<br />
the unit compensation for the supplier’s production<br />
quantities beyond the m<strong>in</strong>imums <strong>in</strong> each period. When<br />
the realized demand exceeds the retailer’s total order,<br />
he will purchase the supplier’s excess <strong>in</strong>ventory, if any,<br />
to meet the market demand at a unit price e .<br />
The sequence of events is summarized as follows:<br />
(1) At the beg<strong>in</strong>n<strong>in</strong>g of period 1, the retailer sets a<br />
firm order d 1 . The retailer also announces an option<br />
contract <strong>with</strong> option prices o 1 and o 2 and exercise<br />
price e. The supplier, <strong>in</strong> turn, decides to produce<br />
q1 d1<br />
of goods <strong>in</strong> the cheap mode which will produce<br />
an <strong>in</strong>come of o1( q1− d1)<br />
.<br />
(2) At the beg<strong>in</strong>n<strong>in</strong>g of period 2, after the market<br />
signal is observed, the retailer orders d 2 . The supplier<br />
selects a second-period production, q2 max{ d− q1,0}<br />
,<br />
that <strong>in</strong>volves the expensive mode and produces an <strong>in</strong>come<br />
of o2( q2 −max{ d − q1,0})<br />
.<br />
(3) At the beg<strong>in</strong>n<strong>in</strong>g of the sell<strong>in</strong>g season, after the<br />
demand is realized, the retailer purchases additionally<br />
m= m<strong>in</strong>{max{ D−d,0}, q− d}<br />
number of goods at<br />
unit price e . The supplier delivers all that the retailer<br />
wants. The problem assumes that the supplier is obligated<br />
to fill the retailer’s entire order and can neither<br />
sell directly to the f<strong>in</strong>al customer (i.e., the retailer’s<br />
customer) nor supply <strong>in</strong>ventory <strong>in</strong> excess of the retailer’s<br />
total order quantity.<br />
With the option contract, the supplier’s problem<br />
becomes<br />
max Π ( q ) = −( c − o ) q + ( w − o ) d +<br />
q1d1 S 1 1 1 1 1 1 1<br />
∫<br />
0<br />
∞<br />
Π ( ε, q , q )d G(<br />
ε),<br />
S 1 2<br />
where ΠS( ε, q1, q2) = max πS( ε,<br />
q1, q2)<br />
and<br />
q2max{ d−q1,0} π ( ε , q , q ) = − c q + o ( q −max{ d − q ,0}) +<br />
S 1 2 2 2 2 2 1<br />
d<br />
wd + vq ( + q − d)d F( x|<br />
ε ) +<br />
∫<br />
2 2<br />
0<br />
1 2<br />
q1+ q2<br />
d<br />
∫<br />
[( ex− d) + vq ( − x)]d Fx ( | ε ) +
WANG Xiaolong (王小龙) et al:<strong>Coord<strong>in</strong>ation</strong> <strong>by</strong> <strong>Option</strong> <strong>Contracts</strong> <strong>in</strong> a <strong>Retailer</strong>-<strong>Led</strong> …<br />
∞<br />
∫ eq ( 1+ q2 −d)d<br />
F( x| ε ).<br />
q1+ q2 Here, ΠS( ε , q1, q2)<br />
represents his second-stage problem.<br />
After mak<strong>in</strong>g the supplier’s second-stage problem<br />
<strong>in</strong>dependent of q 1 and after some algebra, the sup-<br />
plier’s problem is<br />
max Π ( q ) = ( c −c − o + o ) q + ( w − o ) d +<br />
q1d1 S 1 2 1 2 1 1 1 1 1<br />
∫<br />
0<br />
∞<br />
Π ( ε, q )d G(<br />
ε),<br />
S 1<br />
where ΠS( ε, q1) = max πS( ε,<br />
q)<br />
and<br />
qmax{ d, q1}<br />
π S( ε,<br />
q) = ( e− c2+ o2) q+ w2d2−ed−o2max{ d−q1,0} −<br />
q<br />
( e−v) ∫ F( x| ε )d x .<br />
d<br />
N N<br />
Let ( q , q 1 ) denote the solution to this problem, and<br />
then we have Proposition 1.<br />
Proposition 1 Given an option contract specified<br />
<strong>by</strong> the retailer, the supplier’s optimal total production<br />
quantity is<br />
N ⎧ N −1⎛e−<br />
c2 + o2<br />
⎞⎫<br />
q = max ⎨q1, F ⎜ ε ⎟⎬<br />
⎩ ⎝ e−v ⎠⎭<br />
.<br />
The proof is relatively straight forward s<strong>in</strong>ce the supplier’s<br />
problem follows a newsvendor structure.<br />
N<br />
Proposition 1 shows clearly that to coord<strong>in</strong>ate q =<br />
c<br />
e− c2 + o2 p− c2 + s<br />
q , it is necessary to set = , i.e.,<br />
e−v p− v+ s<br />
p− v+ s<br />
e= p+ s− o2<br />
(5)<br />
c2−v Based on Eq. (5), e v e+ o > c to make<br />
> and 2 2<br />
−1⎛ e− c2+ o2<br />
⎞<br />
F ⎜ | ε ⎟ mean<strong>in</strong>gful. Economically these two<br />
⎝ e−v ⎠<br />
conditions prevent the supplier from suffer<strong>in</strong>g losses.<br />
e+ o2is<br />
all the revenue that the supplier can get from<br />
one unit of product if it can be sold after the market<br />
demand is realized. If e+ o2 < c2,<br />
the supplier has no<br />
<strong>in</strong>centive to overproduce <strong>in</strong> the second period, and thus<br />
channel coord<strong>in</strong>ation is never reached. S<strong>in</strong>ce e= p+ s−<br />
p− v+ s<br />
o2<br />
, the two conditions are equivalent <strong>with</strong><br />
c2−v o2 < ( c2 − v)<br />
. Therefore, o2 < ( c2 − v)<br />
from now on.<br />
Next, consider the retailer’s problem. In all the fol-<br />
p− v+ s<br />
low<strong>in</strong>g parts, assume that e= p+ s− o2holds<br />
c2−v except where specified.<br />
The retailer’s problem is<br />
575<br />
∞<br />
max ΠR( d1) =−o1( q1−d1) − wd 1 1+∫ ΠR( ε, d1) d G(<br />
ε),<br />
d10<br />
0<br />
where ΠR( ε, d1) = max πR( ε,<br />
d)<br />
and<br />
dd1 π R( ε , d) = −w2d2 −o2( q2 −max{ d − q1,0})<br />
+<br />
pE m<strong>in</strong>{ D, q} + v( d −Em<strong>in</strong>{ D, d})<br />
−<br />
eE m<strong>in</strong>{max{ D −d,0}, q −d} −<br />
sED ( − Em<strong>in</strong>{ Dq , }).<br />
Rearrang<strong>in</strong>g,<br />
max Π ( d ) = ( o − o ) q + ( w − w + o ) d +<br />
where<br />
d10<br />
R 1 2 1 1 2 1 1 1<br />
∫<br />
∞<br />
Π<br />
0<br />
R( ε, d1)d G(<br />
ε),<br />
ΠR( ε, d1) = max πR( ε,<br />
d)<br />
and<br />
dd R 2<br />
1<br />
π ( ε, d) = ( e−w ) d −( e− v) F( x| ε)dx+<br />
o max{ d − q ,0} + ( p+ s−e−o ) q−<br />
2 1 2<br />
∫<br />
( p+ s−e) F( x| ε )dx−sED.<br />
0<br />
q<br />
N N<br />
Let ( 1 , d d ) denote the optimal solution to the retailer’s<br />
problem. Proposition 2 describes the retailer’s<br />
order<strong>in</strong>g behavior.<br />
e−w2 e− w2 + o2<br />
Proposition 2 Denote α = , β = ,<br />
e−v e−v N −1<br />
N<br />
and γ ( ε) = max{ d1, F (max{ α,0}| ε)}.<br />
Def<strong>in</strong>e ˆ( ε d1<br />
) =<br />
N<br />
N<br />
sup{ ε: Fd ( 1 | ε) max{ α,0}}<br />
and allow ˆ( ε d1<br />
) = +∞<br />
if ε max is <strong>in</strong>f<strong>in</strong>ite. For a given option contract, the<br />
optimal order<strong>in</strong>g behavior for the retailer has the follow<strong>in</strong>g<br />
structure:<br />
(1) After the market signal ε has appeared, the optimal<br />
total order quantity is determ<strong>in</strong>ed as follows:<br />
(i) If Fq ( 1 | ε ) β ,<br />
N<br />
d = γ ( ε ) ;<br />
(ii) Otherwise,<br />
−1<br />
⎧ γε ( ), if πR( ε, F (max{ α,0}| ε))<br />
><br />
⎪ N −1<br />
d = ⎨ πR( ε, F ( β | ε));<br />
⎪⎩ −1<br />
F ( β | ε),<br />
otherwise.<br />
(2) The optimal first-period order quantity is given<br />
<strong>by</strong><br />
N ˆ( ε d1<br />
)<br />
N<br />
2 1 1<br />
0<br />
2 1<br />
∫<br />
w − w + o + [ e−w −( e− v) F( d | ε)]d G(<br />
ε)<br />
= 0<br />
when e+ o1 > w1.<br />
Otherwise, N<br />
d1 ≡ 0 .<br />
Corollary For some second-period option price(s)<br />
−1<br />
o 2 such that β > 0 and set A= { ε : πR( ε, F (max{ α,<br />
−1<br />
0}| ε )) π ( ε, F ( β | ε))}<br />
is not empty, there exists a<br />
R<br />
∫<br />
0<br />
d
576<br />
signal T ( 2)<br />
o ε such that<br />
N −1<br />
only if T ( 2)<br />
o ε ε<br />
greater than 1 q and T ( 2) max o ε ε<br />
d = F ( β | ε)<br />
> q1if<br />
and<br />
<br />
N<br />
. Otherwise, d will never be<br />
= for such cases.<br />
Proof First, prove part (1). Omitt<strong>in</strong>g all the irrelevant<br />
parts, the retailer’s second-period problem can be<br />
rewritten as<br />
d<br />
⎧( e−w2) d −( e−v) F( x| ε )d x,<br />
⎪ ∫ 0<br />
⎪ if dq1; max πR( ε,<br />
d)<br />
= ⎨<br />
dd d<br />
1 ⎪( e− w2 + o2) d −( e−v) F( x| ε )d x,<br />
0<br />
⎪<br />
∫<br />
⎪⎩ otherwise.<br />
Then, the unconditional optimal N<br />
d may not be<br />
unique but can be either<br />
−1<br />
F (max{ α,0}| ε ) or<br />
−1<br />
N −1<br />
F (max{ β,0}| ε ) or both. However, if d = F ( β | ε ) ,<br />
−1<br />
there must be F ( β | ε)<br />
> q1,<br />
i.e., 0 < Fq ( 1 | ε ) < β , so<br />
that max{ d − q1,0} = d − q1<br />
makes sense. This completes<br />
the proof of part (i) when Fq ( 1 | ε ) β and<br />
N<br />
d = γ ( ε ) .<br />
Now consider 0 < Fq ( 1 | ε ) < β . The criterion is sim-<br />
N<br />
ple but clear. Whether d = γ ( ε ) or N 1 −<br />
d = F ( β | ε )<br />
depends on which can br<strong>in</strong>g more expected profit, i.e.,<br />
−1<br />
⎧ γε ( ), if πR( ε, F (max{ α,0}| ε))<br />
><br />
⎪ N −1<br />
d = ⎨ πR( ε, F ( β | ε));<br />
⎪⎩ −1<br />
F ( β | ε),<br />
otherwise.<br />
This completes the proof of part (1) <strong>in</strong> Proposition 2.<br />
Next, show the l<strong>in</strong>k between the retailer’s second-period<br />
expected profit and the market signal to<br />
estimate the optimal total order from the beg<strong>in</strong>n<strong>in</strong>g of<br />
period 1 based on the market signal conditions, which<br />
is the core idea of the corollary.<br />
−1<br />
When β > 0, let π ( ε, F (max{ α,0}| ε)) = π ( ε,<br />
−1<br />
F ( β | ε )) . Note that<br />
R R<br />
d ≡ d when β 0 because<br />
N N<br />
1<br />
β α . Suppose that there exists a solution T ( 2)<br />
o ε ,<br />
and then for T ( 2)<br />
o ε the retailer is <strong>in</strong>different towards<br />
the choice of<br />
1 −<br />
−1<br />
F (max{ α,0}| ε ) and F ( β | ε ) . Obviously,<br />
for stronger signals T ( 2),<br />
o ε ε ><br />
N −1<br />
d = F ( β | ε ) ><br />
q 1 . Otherwise, if such a T ( 2)<br />
o ε does not exist, or<br />
−1 −1<br />
equivalently, πR( ε, F (max{ α,0}| ε)) > πR( ε,<br />
F ( β | ε ))<br />
for any signals, def<strong>in</strong>e T ( 2) max o<br />
N<br />
ε = ε . Thus, d =<br />
−1<br />
F ( βε | ) > q1is<br />
impossible because the market signal<br />
cannot be greater than its maximum.<br />
Ts<strong>in</strong>ghua Science and Technology, August 2008, 13(4): 570-580<br />
Next consider part (2) which depicts the first-period<br />
order<strong>in</strong>g behavior. If o2=0, then the retailer’s second-period<br />
problem is given <strong>by</strong> the follow<strong>in</strong>g:<br />
For any α , similar to the reason<strong>in</strong>g <strong>in</strong> proof of<br />
Lemma 1,<br />
d is implied <strong>by</strong><br />
2 1 1<br />
N<br />
1<br />
N ˆ( ε d1<br />
)<br />
∫ 0<br />
2<br />
N<br />
1<br />
α , i.e., e w2<br />
N<br />
1<br />
w − w + o + [ e−w −( e− v) F( d | ε)]d G(<br />
ε)<br />
= 0.<br />
Particularly, when 0 , <strong>in</strong>equality<br />
Fd (<br />
N<br />
| ε ) 0 holds for any signal ε , then ˆ( ε d1<br />
)<br />
must be equal to ε max , which is <strong>in</strong>f<strong>in</strong>ite <strong>in</strong> our model.<br />
Under such cases, we can rewrite the above equation<br />
as<br />
+∞<br />
N<br />
2 1 1<br />
0<br />
2 1<br />
∫<br />
w − w + o + [ e−w −( e− v) F( d | ε)]d G(<br />
ε)<br />
= 0.<br />
Rearrang<strong>in</strong>g,<br />
+∞<br />
N<br />
1 1<br />
0<br />
1<br />
∫<br />
e− w + o −( e− v) F( d | ε)d G(<br />
ε)<br />
= 0.<br />
Note that 0<br />
∞<br />
N<br />
∫ Fd (<br />
0<br />
1 | ε)d G(<br />
ε)<br />
1<br />
special cases when e+ o1 w1<br />
, then<br />
. There are some<br />
N N<br />
d = d1=<br />
0.<br />
Note that e− w1+ o1 e−v cannot succeed because<br />
it requires o1 w1−v, which would <strong>in</strong>centivize the<br />
supplier to produce <strong>in</strong>f<strong>in</strong>itely <strong>in</strong> period 1 and, thus, is<br />
ridiculous.<br />
In summary, the optimal first-period order quantity<br />
d is given <strong>by</strong><br />
N<br />
1<br />
N ˆ( ε d1<br />
)<br />
N<br />
2 1 1<br />
0<br />
2 1<br />
∫<br />
w − w + o + [ e−w −( e− v) F( d | ε)]d G(<br />
ε)<br />
= 0<br />
N<br />
when e+ o1 > w1.<br />
Otherwise, d1 ≡ 0 . □<br />
Proposition 2 shows that the retailer’s order<strong>in</strong>g behavior<br />
is closely l<strong>in</strong>ked to the option price o 2 and the<br />
market signal ε . Different option prices result <strong>in</strong> different<br />
order<strong>in</strong>g behavior. Under some circumstances,<br />
the optimal total order may not even be unique. Signals<br />
such as ˆε and ε T can be used to categorize the retailer’s<br />
orders. These mark<strong>in</strong>g signals are important <strong>in</strong><br />
models concerned <strong>with</strong> demand <strong>in</strong>formation update.<br />
The conclusion <strong>in</strong> the corollary is mean<strong>in</strong>gful for disclos<strong>in</strong>g<br />
the relationship between the retailer’s second-period<br />
profit curve and the market signal that optimal<br />
total order more than q 1 is possible if and only<br />
if T ( 2) max o ε ε < exists. T ( 2)<br />
o ε must be always greater<br />
than ε ( q1)<br />
for a given q 1 because the conservative<br />
retailer has <strong>in</strong>centive to choose an optimal total order<br />
greater than q 1 <strong>with</strong> T ( 2)<br />
o ε that he will never do
WANG Xiaolong (王小龙) et al:<strong>Coord<strong>in</strong>ation</strong> <strong>by</strong> <strong>Option</strong> <strong>Contracts</strong> <strong>in</strong> a <strong>Retailer</strong>-<strong>Led</strong> …<br />
N * c<br />
<strong>with</strong> ε ( q1)<br />
because d d < q . A f<strong>in</strong>al <strong>in</strong>terest<strong>in</strong>g<br />
N<br />
issue is that d is not cont<strong>in</strong>uous <strong>in</strong> ε for a given<br />
contract and q 1 is a k<strong>in</strong>k po<strong>in</strong>t of the retailer’s expected<br />
profit function. No matter what the realized<br />
market signal is, the optimal total order never equals<br />
1 . q This may occur <strong>with</strong> the mechanism which sets the<br />
second-period compensation <strong>in</strong>come to be max{ d− q1,<br />
0}.Thus, the derivative of π R ( ε,<br />
d)<br />
will never be equal<br />
to zero at q 1 .<br />
Now, consider the supplier’s problem. Know<strong>in</strong>g the<br />
retailer’s order<strong>in</strong>g behavior, the supplier will set his<br />
first-period production quantity accord<strong>in</strong>gly. When the<br />
retailer knows the supplier’s first-period production<br />
decision (which is related to the retailer’s order<strong>in</strong>g be-<br />
c<br />
havior), the retailer coord<strong>in</strong>ates it to be equal to q 1 <strong>by</strong><br />
modify<strong>in</strong>g o 1 . This is the standard Stackelberg game.<br />
Comb<strong>in</strong><strong>in</strong>g Eq. (5), the overall f<strong>in</strong>d<strong>in</strong>gs for coord<strong>in</strong>ation<br />
are summarized <strong>in</strong> Proposition 3.<br />
e−w2 Proposition 3 Denote α = and β =<br />
e−v e− w2 + o2<br />
. To coord<strong>in</strong>ate the channel, ensure that<br />
e−v o2 < c2 − v and ma<strong>in</strong>ta<strong>in</strong> some specific functional relationships<br />
between the contract parameters of 1 o , o 2 ,<br />
and e .<br />
p− v+ s<br />
e= p+ s− o2and<br />
c2−v ⎡ c2 − c1⎤<br />
o1 =<br />
⎢<br />
G( εT<br />
( o2)) − o2<br />
c2−v ⎥ ,<br />
⎣ ⎦<br />
where T ( 2)<br />
o ε is determ<strong>in</strong>ed <strong>by</strong><br />
−1<br />
πR( εT( o2), F (max{ α,0}| εT(<br />
o2)))<br />
=<br />
−1<br />
πR( εT( o2), F ( β | εT(<br />
o2)))<br />
when β > 0 and<br />
−1<br />
{ εT( o2) : πR( εT( o2), F (max{ α,0}| εT( o2))) = πR( εT(<br />
o2),<br />
−1<br />
F ( β | εT(<br />
o2)))}<br />
≠∅. Otherwise, def<strong>in</strong>e T ( 2) max o ε = ε .<br />
Proof The necessity of equation e= p+ s−<br />
p− v+ s<br />
o2<br />
was proved <strong>in</strong> Proposition 1. Next, show<br />
c2−v that coord<strong>in</strong>ation still needs another condition,<br />
⎡ c2 − c1⎤<br />
o1 =<br />
⎢<br />
G( εT<br />
( o2)) − o2<br />
c2−v ⎥ .<br />
⎣ ⎦<br />
Recall that <strong>in</strong> this model coord<strong>in</strong>ation means<br />
N c<br />
N c<br />
q = q and q1 = q1<br />
. Based on the corollary <strong>in</strong><br />
Proposition 2, write the first-order condition for the<br />
optimal<br />
N<br />
q 1 as<br />
2 1 2 1<br />
ε ( q1<br />
)<br />
0<br />
2 2 1<br />
∫<br />
577<br />
c − c − o + o + [ e− c + o −( e− v) F( q | ε )]d G(<br />
ε ) +<br />
∫<br />
∞<br />
o<br />
(<br />
2d<br />
G(<br />
ε ) = 0.<br />
εT<br />
o2 )<br />
p− v+ s<br />
Substitute e= p+ s− o2<strong>in</strong>to<br />
this equation<br />
c2−v and rearrange<br />
⎛ o ( 1)<br />
2 ⎞ ε q<br />
c2 − c1− o2 + o1+ ⎜1 − [ p− c<br />
0<br />
2 + s−<br />
c2−v ⎟<br />
⎝ ⎠ ∫<br />
∞<br />
( p− v+ s) F( q | ε)]d G( ε) + o d G(<br />
ε)<br />
= 0.<br />
Compar<strong>in</strong>g <strong>with</strong><br />
1<br />
T ( 2 )<br />
2<br />
o ε<br />
c<br />
ε ( q1<br />
)<br />
2 1<br />
0<br />
2<br />
∫<br />
∫<br />
c − c + [ p− c + s−( p− v+<br />
c<br />
N c<br />
sFq ) ( 1 | ε)]d G(<br />
ε ) = 0,<br />
to let q1 = q1<br />
, set o 1 so that<br />
the follow<strong>in</strong>g equality holds:<br />
c o ε ( q1<br />
)<br />
2<br />
− o2+ o1− [ p− c<br />
0<br />
2+ s−( p− v+ s) F( q1| ε )]d G(<br />
ε ) +<br />
c −v∫ Note that<br />
2<br />
∫<br />
∞<br />
o d G(<br />
ε ) = 0.<br />
o<br />
ε (<br />
2<br />
T 2 )<br />
c<br />
ε ( q1<br />
)<br />
c<br />
2− 1+ − 2+ − − + 1<br />
0<br />
c c ∫ [ p c s ( p v s) F( q | ε )]d G(<br />
ε ) = 0<br />
and rearrang<strong>in</strong>g gives<br />
⎡ c2 − c1⎤<br />
o1 =<br />
⎢<br />
G( εT<br />
( o2)) − o2<br />
c2−v ⎥ . □<br />
⎣ ⎦<br />
There are the pric<strong>in</strong>g equations which assure channel<br />
profit maximization. However, an important issue<br />
to be considered before implement<strong>in</strong>g any new pric<strong>in</strong>g<br />
scheme is whether the scheme is Pareto improv<strong>in</strong>g<br />
<strong>with</strong> respect to an exist<strong>in</strong>g policy. In other words, will<br />
both the retailer and the supplier be better off <strong>with</strong> the<br />
proposed policy? To shed light on this question, exam<strong>in</strong>e<br />
how the retailer’s and supplier’s expected profits<br />
change as the contract parameters vary.<br />
Unfortunately, due to the model complexity, closed<br />
form solutions are not possible for some of the key<br />
variables; thus, quantitative comparisons are almost<br />
impossible. We cannot even prove that the monotonicity<br />
of each side’s expected profit function as o 2 varies<br />
because it is related to the specific forms of the distribution<br />
functions.<br />
3 Example<br />
Suppose that F and G are both uniform distribution<br />
functions <strong>with</strong> F~ U( a, b ) and G~ U(0, t ) . The critical
578<br />
factor <strong>in</strong> models consider<strong>in</strong>g demand update is how the<br />
market signal updates the demand <strong>in</strong>formation, i.e.,<br />
how to def<strong>in</strong>e F( x| ε ) . Make the follow<strong>in</strong>g assumptions<br />
related to the market signal:<br />
(1) The market signal does not change the demand<br />
distribution pattern, i.e., F( x| ε ) is still uniform.<br />
(2) The market signal only affects the mean of the<br />
demand distribution, not the variance. As the signal<br />
becomes stronger the mean shifts up accord<strong>in</strong>gly. For<br />
uniform distributions, this implies that if F( x| ε ) ~<br />
U( f1( ε ), f2(<br />
ε )), then f2( ε) − f1( ε)<br />
≡b−a and f1 ( ε ) and<br />
f2 ( ε ) are both <strong>in</strong>creas<strong>in</strong>g <strong>in</strong> ε .<br />
(3) A market signal as mathematically expected<br />
ma<strong>in</strong>ta<strong>in</strong>s the orig<strong>in</strong>al demand distribution function.<br />
That is, if ε = 0.5t , then F( x| ε ) = F( x)<br />
. Moreover,<br />
assume<br />
F( x| ε )~ U( a−4(0.5 t−ε), b−4(0.5 t−<br />
ε))<br />
.<br />
To avoid un<strong>in</strong>terest<strong>in</strong>g cases, def<strong>in</strong>e a> 2t.<br />
Consider the follow<strong>in</strong>g numerical example. Suppose<br />
the orig<strong>in</strong>al demand distribution is uniform <strong>with</strong><br />
a = 1000 and b = 2000 . The market signal is uniformly<br />
distributed between zero and t = 150.<br />
The cost<br />
parameters are c1= 50, c2= 65, w1= 60, w2= 80, v=<br />
20,<br />
s = 30,<br />
and p = 100 .<br />
For any o 2 ,<br />
p− v+ s<br />
e= p+ s− o .<br />
(1) Calculate e accord<strong>in</strong>g to<br />
(2) Solve for T ( 2)<br />
c2−v 2<br />
o ε .<br />
If β > 0 , εT( o2)<br />
= m<strong>in</strong>{150, ε′ T},<br />
where T<br />
ε′ is determ<strong>in</strong>ed<br />
<strong>by</strong><br />
−1 −1<br />
π R( ε′ T, F (max{ α,0}| ε′ T)) = πR( ε′ T, F ( β | ε′<br />
T))<br />
;<br />
If β 0 , T ( 2)<br />
150. o ε =<br />
⎡<br />
(3) Calculate o 1 accord<strong>in</strong>g to o1 = ⎢G(<br />
εT<br />
( o2))<br />
−<br />
⎣<br />
c2 − c1 ⎤<br />
o2<br />
c2−v ⎥ .<br />
⎦<br />
N<br />
(4) Solve for d 1 .<br />
N<br />
If e+ o1 w1,<br />
d1 ≡ 0 ;<br />
If e+ o1 > w1,<br />
substitute<br />
N<br />
N d1−[ a− 2 t+ ( b−a)max{ α,0}]<br />
ˆ( ε d1<br />
) = (which is<br />
4<br />
N N<br />
derived from Fd ( | ˆ ε( d )) = max{ α,0}<br />
) <strong>in</strong>to<br />
1 1<br />
N ˆ( ε d1<br />
)<br />
N<br />
2 1 1 ∫ 0<br />
2 1<br />
w − w + o + [ e−w −( e− v) F( d | ε)]d G(<br />
ε)<br />
= 0.<br />
Ts<strong>in</strong>ghua Science and Technology, August 2008, 13(4): 570-580<br />
If ˆ( ε d ) < 150,<br />
the results can be directly used.<br />
If ˆ( ε d ) 150,<br />
then<br />
N<br />
1<br />
N<br />
1<br />
N<br />
d 1 is implied <strong>by</strong><br />
150<br />
N<br />
2 1 1<br />
0<br />
2 1<br />
∫<br />
w − w + o + [ e−w −( e− v) F( d | ε)]d G(<br />
ε)<br />
= 0.<br />
(5) Calculate each party’s expected profit.<br />
Figure 1 shows how the retailer’s first-period order<br />
changes as o 2 varies. As expected, the retailer sets<br />
N<br />
d ≡ 0 when 1 1 , e o w<br />
o <br />
1<br />
p− w1+ s<br />
c2v p− c1+ s<br />
+ or equivalently, 2<br />
( − ) = 39.375.<br />
Such an order<strong>in</strong>g behavior<br />
directly <strong>in</strong>fluences each party’s expected profit curve<br />
shown <strong>in</strong> Fig. 2.<br />
Fig. 1 <strong>Retailer</strong>’s optimal first-period order quantity<br />
Figure 2 compares each party’s expected profit after<br />
coord<strong>in</strong>ation <strong>with</strong> that before coord<strong>in</strong>ation which is<br />
shown <strong>by</strong> the benchmark curve. The powerful retailer,<br />
who acts as a contract designer, will never be worse off,<br />
but the results are not so optimistic. The supplier’s expected<br />
profit even becomes negative for some cases!<br />
Notably, <strong>with</strong> these sett<strong>in</strong>gs, the first-best expected<br />
c<br />
profit Π = 221 209.<br />
Before coord<strong>in</strong>ation, however,<br />
Π R = 175 960 and Π S = 16 437. This leaves an improvement<br />
of 28 812 which is almost twice the supplier’s<br />
expected profit before coord<strong>in</strong>ation.<br />
Fig. 2 Expected profit for each party before and after<br />
coord<strong>in</strong>ation
WANG Xiaolong (王小龙) et al:<strong>Coord<strong>in</strong>ation</strong> <strong>by</strong> <strong>Option</strong> <strong>Contracts</strong> <strong>in</strong> a <strong>Retailer</strong>-<strong>Led</strong> …<br />
Table 1 illustrates the profit allocation issues <strong>in</strong> detail.<br />
For these calculations, the new contract is feasible<br />
only when 34.8o2 43.8.<br />
For low o 2 <strong>in</strong> this range,<br />
each party becomes strictly better off. In particular,<br />
consider the best profit allocation situations for which<br />
each side gets a double-digit share of the extra profit.<br />
When o 2 is around 40, the supplier will get more<br />
than 60% of the extra system profit which is double<br />
what he earned before coord<strong>in</strong>ation. Such a rosy profit<br />
improvement surely offers a strong <strong>in</strong>centive for the<br />
supplier to accept the new contract. Most <strong>in</strong>terest<strong>in</strong>gly,<br />
such profit allocations correspond to o2 39.6 which<br />
N N<br />
implies e+ o1 w1<br />
and d = d1=<br />
0. Thus, order<br />
postponement (until the demand uncerta<strong>in</strong>ty is resolved)<br />
can be beneficial to each party. This is contrast<br />
to the traditional thought that suppliers always welcome<br />
as-early-as-possible orders. Our op<strong>in</strong>ion is that<br />
suppliers hate late orders mostly because they make<br />
the work of arrang<strong>in</strong>g production schedules more difficult.<br />
However, a properly designed <strong>in</strong>centive mechanism,<br />
which both clarifies the quantity that the supplier<br />
should produce and br<strong>in</strong>gs extra profit, elim<strong>in</strong>ates<br />
these negative concerns. Such a result, however, needs<br />
further proof from theory and practice.<br />
Table 1 Profit allocations between the two parties<br />
Extra profit allocation on supplier<br />
Second-period option price<br />
(% of improvement scope)<br />
0 100<br />
34.8 1<br />
… …<br />
39.6 67<br />
39.9 63<br />
40.2 58<br />
40.5 53<br />
40.8 48<br />
41.1 44<br />
41.4 39<br />
41.7 35<br />
42.0 30<br />
42.3 26<br />
… …<br />
43.8 3<br />
Note: For simplicity, we state here only the allocation status for the supplier.<br />
Its counterpart for the retailer can be calculated s<strong>in</strong>ce the sum is equal<br />
to 1.<br />
4 Conclusions<br />
579<br />
This analysis considers the coord<strong>in</strong>ation of option contracts<br />
<strong>in</strong> a retailer-led supply cha<strong>in</strong> where the retailer<br />
designs the contract and the supplier’s production<br />
needs to be coord<strong>in</strong>ated <strong>with</strong> the contract. Consider the<br />
case where the supplier operates two modes of production<br />
and the retailer has the ability to update the demand<br />
forecast as the sell<strong>in</strong>g season approaches. With<strong>in</strong><br />
this contract class, a set of pric<strong>in</strong>g conditions are def<strong>in</strong>ed<br />
that align the supplier and retailer to act <strong>in</strong> the<br />
best <strong>in</strong>terests of the channel. The analysis leads to<br />
some <strong>in</strong>terest<strong>in</strong>g results.<br />
First, option prices should be negatively correlated<br />
to the price and should be <strong>in</strong> a relevant range. This<br />
gives a trade-off between the higher unit compensation<br />
the supplier requires and the lower repurchas<strong>in</strong>g price<br />
he will get. To assure that the option mechanism is an<br />
effective <strong>in</strong>centive, the option prices should be <strong>with</strong><strong>in</strong> a<br />
relevant range. The second-period option price should<br />
be no greater than the difference between the second-<br />
period unit production costs and the salvage value.<br />
Otherwise, the supplier will earn little due to the rapidly<br />
decreas<strong>in</strong>g exercise price and the coord<strong>in</strong>ation will<br />
fail.<br />
Second, the first-period option price should be no<br />
greater than the second-period price and should be<br />
l<strong>in</strong>early correlated to the second-period option price<br />
when the latter is beyond some threshold. This result is<br />
true regardless of the specific functional form of the<br />
market demand or market signal.<br />
Third, the retailer’s order<strong>in</strong>g behavior is <strong>in</strong>fluenced<br />
<strong>by</strong> the dual effect of the predictive power of the new<br />
market <strong>in</strong>formation and option prices. Some extreme<br />
pric<strong>in</strong>g cases may result <strong>in</strong> the order<strong>in</strong>g behavior be<strong>in</strong>g<br />
<strong>in</strong>dependent of the new market <strong>in</strong>formation. The <strong>in</strong>fluence<br />
pattern is so complex that there is no closed<br />
form solution to the retailer’s first-period optimal order<br />
quantity. Fortunately, this does not prevent explor<strong>in</strong>g<br />
the optimal pric<strong>in</strong>g conditions which are stated <strong>in</strong><br />
Proposition 3. A numerical example is given for the<br />
profit allocation issues. An <strong>in</strong>terest<strong>in</strong>g result is that<br />
order postponement may be beneficial to both parties,<br />
though this needs further theoretical proof.
580<br />
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