PART II Solutions

1. PART II Solutions 4 Supply Chains as Systems

2. Supply Chains as Systems(供應鏈系統觀) Integrating a supply chain requires assembling an ad hoc collection of facilities into a coherent system that can function with a single purpose. In order to succeed in this effort, you need to know something about systems—how they are designed, how they work, and how they are controlled. In short, you need a little systems theory. This may sound like an abstract subject of limited relevance to your needs, but nothing could be further from the truth. As a manager, you deal with some of the most complex systems on earth every day, and your experience has already given you a basic understanding of how these systems work. The problem with this understanding is that it's largely intuitive, making it hard to use in solving new problems. This chapter will help you hone those intuitions into powerful business design tools. 整合供應鏈需要將一些設施以特有方式組合起來，成為一個可以朝共同目 標努力的一致性系統(a coherent system)。為使上述努力可以成功，你必須 瞭解系統運作原理──如何設計它們、它們如何運作，以及它們如何被控 制。總之，你需要懂得一些系統理論(systems theory)。這聽起來好像一個 抽象主題，與你的需求關聯性不高，但事實不然。身為一個經理人，你每 天都在面對一些最複雜的系統，你的經驗已經給予你這些系統如何運作的 一個基礎性理解。這種理解的缺點是它們絕大部分是一種直覺，很難用來 解決新問題。本章將幫助你磨練你的直覺，使之成為有力的商業設計工 具。

3. Business Cybernetics(商業系統控制學) A system is an assembly of components The formal study of systems dates back to the 1940s with the emergence of cybernetics, which took insights gained from the invention of computers and applied them to other domains. In cybernetics, a system is viewed as an assembly of Components that interact to produce collective behavior. Computers are systems, of course, but so are plants, animals, ecologies, nations, companies, factories, and, yes, supply chains. The key insight of cybernetics is that there are common principles across all these different kinds of systems, principles that help explain the behavior of each. Knowing something about systems in general really does help you understand business systems in particular. 一個系統是由許多元件組合而成 正式的系統研究可以回溯到1940年代，並形成了系統控制學 (cybernetics)，將從電腦發明所得到的洞察力應用在其他領域上。在系統 控制學中，一個系統(system)被視為一些元件(components)的組合，元件間 其互動性並產生集體行為。電腦當然是系統，但是植物、動物、生態、國 家、公司、工廠也都是，供應鏈當然也是。系統控制學重要的洞察力在 於，不同類型系統間存在共通性的原則(common principles)，這些原則可 以幫助我們解釋系統的行為。瞭解系統的一般性原則將有助於瞭解更特殊 的商業系統。

4. Business Cybernetics(商業系統控制學) A system transforms inputs into outputs One of the key contributions of cybernetics was the insight that all systems can be seen as transforming inputs into outputs. When systems are constructed by people, as supply chains are, they are usually designed to produce outputs that have greater immediate value than the inputs. For example, computers take in large volumes of data and distill it into useful information; factories consume raw materials and produce finished goods; human beings take in food and transform it into . . . well, some improvements are less obvious than others. In this case, the output of interest is the energy extracted from the food, which in turn is transformed into physical movement and other forms of work. 一個系統將投人轉換成產出 系統控制學的一個主要貢獻，是洞察到所有系統均可視為將投入(input)轉 換為產出(output)的活動。當系統被人建構起來時，例如供應鏈，它們通 常被設計來立即產生比投入資源更高價值的產出。例如，電腦取得大筆的 資料並且處理成有用的資訊；工廠消耗原料並且產生成品；人類吃下食物 並產生成……好了，有些改善與其他的相比較不明顯。上述最後一例，產 出是從食物中萃取出的能量，再轉換成我們的動能和其他型態的工作。

5. Business Cybernetics(商業系統控制學) System may have controls and monitors Natural systems, such as ecologies, are usually self-regulating, and attempts to control them often do more harm than good. Systems made by people, on the other hand, are designed to be controlled and monitored so that their performance can be improved over time. Control is achieved by regulating the flow of inputs, and monitoring involves measuring the resulting outputs. In effect, these systems have the equivalent of knobs on their inputs and gauges on their outputs; changing the settings of the knobs changes the readings on the gauges (Figure 4.1). Inside the system, a number of components—which may be systems in their own right—interact to transform the inputs into the outputs. If the arrangement of the components in the illustration suggests the structure of a supply chain, that's probably not a coincidence. 系統可以其有控制力與監督力 自然系統，例如生態系統(ecologies)，經常具自我調節能力，試圖去控制 它們常帶來更壞的結果。反之，人造系統是被設計來做控制與監督的，以 致於它們的績效可以不斷地改進。控制力是由管制投入流程(或流量)而達 成，監督力涉及對產出結果的評量。在效果上，這些系統的投入相當於轉 鈕(knobs)，產出相當於量表(gauges)；改變轉鈕的設定就會改變量表的讀 數(readings)(見圖4.1)。在系統裡，有些元件──本身可能就是系統──經 互動後將投入轉換為產出。假如圖例中的元件安排讓人聯想到供應鏈架構 的話，這可能不僅是一種巧合。

6. Business Cybernetics(商業系統控制學) System may have controls and monitors A System

7. Business Cybernetics(商業系統控制學) Not all inputs are subject to control Notice in Figure 4.1 that not all the inputs have knobs, and not all the outputs have gauges. Even in the best-designed systems, there are usually some inputs that can't be controlled by the people operating the system. In the case of supply chains, economic cycles and natural disasters can have a profound impact on performance, but these are outside the span of control. Economists call these inputs extrinsic factors because, in Contrast to intrinsic factors such as plant capacity and budget allocations, they originate from outside the boundaries of the system. 不是所有投入都需要控制 注意圖4.1不是所有投入都有轉鈕，也不是所有產出都有量表，甚至在最 佳設計的系統裡，經常有些投入無法由操作系統的人控制。在供應鏈的情 況中，經濟週期和自然災害可能對績效造成深遠的影響，但是它們卻是企 業所無法控制的。經濟學者稱這些投入為外部因素(extrinsic factors)，與 工廠產能和預算分配等內在因素(intrinsic factors)成對比，因為它們來自 於系統界線之外。

8. Business Cybernetics(商業系統控制學) Monitoring outputs is a matter of selection Similarly, it may not be possible to measure every output of a system. For example, measuring the contribution to consumer value added by each stage of a production process is highly desirable but notoriously difficult in most industries. Even if it is possible to measure every output, systems usually have so many outputs that it's not cost-effective to measure them all. The preferred approach, then, is to measure the set of outputs that are most helpful in monitoring and controlling the system. The problem of choosing the best set of outputs to measure is particularly Difficult in the case of supply chains (see Chapter 9). 產出之監督攸關於選擇 同樣地，我們不一定能夠評量每一個系統的產出。例如，評量每一生產階 段產生的消費者附加價值貢獻度是大家都想做的，但是大部分產業都存在 很大的困難加以評量。即使有可能評量每一個產出，系統通常有很多的產 出，一一加以評量是非常不其成本效益的工作。較佳的方法是評量對系統 之監督與控制最有幫助的那些產出項目(the set of outputs)。選擇評量所需 最佳產出項目這個工作，在供應鏈情況中又特別的困難(見第9章)。

9. Business Cybernetics(商業系統控制學) The first goal is understanding a system With just these few concepts in place, it's already possible to see why an understanding of systems is useful in managing supply chains. In essence, each manager in the chain is given responsibility for a set of knobs, and each one sees the readings on a set of gauges. The goal is for everyone to set their knobs just right in order to maximize the outputs of the chain. That isn't going to happen without some shared understanding of how the settings affect the operation of the chain, together with some coordination of the changes to get the best overall performance. 首要目標是要瞭解系統 藉由這幾個少數的觀念，已經可以看出為何瞭解系統有助於供應鏈之管 理。本質上，供應鏈上的每一位經理人都被賦予一組轉鈕(a set of knobs) 的責任，每一個人都可以看到量表(gauges)上的讀數(readings)。每個人的 目標是將轉鈕設定在正確位置，使供應鏈的產出最大化。如果成員間對這 些設定將如何影響供應鏈運作沒有共同的瞭解，並在成員間為得到最佳整 體績效的改變做好協調的話，這些事情將不可能發生。

10. Business Cybernetics(商業系統控制學) Understanding permits prediction and control Figure 4.2 illustrates how this works by showing the relationships among three key processes in managing systems: understanding, prediction, and control. Understanding provides the insights necessary for you to predict how a system will behave in response to changes to its inputs. Prediction, in turn, allows you to control the system by making the best combination of adjustments. Comparing predicted with actual results deepens your understanding of the system, allowing you to make more accurate predictions and improving your control. Together, these core processes form the heart of any successful management process. 瞭解後將可進行預測與控制 圖4.2說明管理系統申三樣重要的程序之間的關係是如何運作：瞭解 (understanding)、預測(prediction)和控制(control)。瞭解提供了你所需的洞 察力去預測一個系統如何依據投入的改變而表現。接著，預測藉由做出最 佳的調整組合允許你去控制系統。比較預測與實際結果可以加深對系統的 瞭解，允許你去做出更多精確預測和改進你的控制。這些核心程序共同塑 造出任何成功管理程序的重心。

11. Business Cybernetics(商業系統控制學) Understanding permits prediction and control Understanding, Prediction, And Control

12. Business Cybernetics(商業系統控制學) Understanding is usually neglected Of the three processes, understanding is arguably the most important, yet it is also the most neglected. Instead, the emphasis proceeds in the other direction: Control is the primary concern, prediction is invoked only as needed to improve control, and understanding is viewed as an incidental by-product rather than the prime mover of the sequence. This reversal of priorities may be necessary in the short run, but it is self-defeating in the long haul. The image that comes to mind is driving a tandem truck down the freeway in reverse, making wild corrections to the steering in order to compensate for going about the matter backward. This book—not to mention my entire career—is devoted to getting understanding back out in front where it belongs. 瞭解這個階段往往受到忽略 在這三個程序中，瞭解可以說是最重要的，然而卻是最被忽略的。相反 地，企業強調的卻是其他兩方面的程序：控制是主要的關注焦點，預測只 有在需要時才會被使用來改善控制；瞭解被看成是一種附帶產生的結果， 而不是排序中的第一個。這樣優先順序的顛倒，短期可能有效，但是長期 而言卻會帶來自我挫敗。我們即刻想到的影像是，在高速公路上駕著一輛 貨車反向行駛，狂野地旋轉著方向盤欲更正方向，以彌補一開始反向行駛 的錯誤行為。這本書──更不用談筆者的整個人生──是致力於將瞭解拉 回它所應有的前面順位。

13. Business Cybernetics(商業系統控制學) Some systems don’t require understanding To be fair, some systems are so well designed that very little understanding is required to control them. Contemporary cars epitomize such systems, at least in regard to the basic controls. The harder you press on the gas pedal, the faster the car goes. The machinery and software that intervene between this input and the resulting output have become extremely complex over the years, but the mapping between the two is so straightforward that operators don't need to know a thing about the internals of the system. In computer terms such systems are referred to as being user-friendly, a state that remains an elusive goal for computers themselves. 有些系統是不需要瞭解的 事實上，有些系統設計得非常好，不需要太多瞭解就可以控住它們。現代 化汽車可作為此類系統之例，至少在基本控制方面。油門踩得愈用力，車 子就跑得愈快。介於這個投入(踩油門)與所獲產出(車速)間的機器跟軟 體，在過去幾年已變得極端複雜，但是這兩者間的關聯性非常直截了當， 以致於駕駛人根本無須瞭解內部系統的任何事情。在電腦術語中，這樣的 系統被稱為好的使用者介面(user-friendly)，這種狀態仍然是電腦難以企及 的目標。

14. Business Cybernetics(商業系統控制學) Understanding is essential for supply chains Supply chains are anything but user-friendly. The basic mechanics. as described in Chapter 2, are pretty simple, but the behavior of the chain as a whole can be very difficult to understand, much less predict and control. One of the recurring themes of this book is that even the most benign attempts to control supply chains, such as offering quantity discounts to encourage volume purchases or running promotions to increase sales, can have wholly unintended and often disastrous effects on performance. When it comes to systems of this level of complexity, understanding is not a luxury; it's a necessity. 瞭解是供應鏈所必要的 供應鏈的使用者介面非常不理想。基本運作機制(basic mechanics)(已在第2 章介紹)是非常簡單的，但是整個供應鏈的行為卻是很難瞭解的，預測與 控制就更加困難了。這本書不斷重提的一個主體思維是，即便以最善意的 嘗試來控制供應鏈，例如，提供數量折扣鼓勵大量採購或執行促銷活動增 加銷售，經常會帶來在績效上完全意想不到甚至是非常嚴重的效果。當我 們面對的是這麼複雜的系統時，瞭解不是一項奢侈品(a luxury)而是一項必 需品(a necessity)。

15. A Rogues Gallery of Relations(淘氣鬼關係陳列館) Relations map inputs to outputs One of the most basic characteristics of systems is the way in which they map values on the inputs to values on the outputs. This mapping, or relation, can take on a variety of different types, which range from the most straightforward to the truly bizarre. This section introduces you to the various kinds of relations you might encounter, using a device I call the Rogues Gallery of Relations. 關係用於呈現投入與產出之關聯性 系統最基本的特性之一，就是它們將投入值轉換成產出值所用的方式。這 個關聯性(mapping)或關係(relation)，可以有數種不同的型態，範圍從最直 截了當到非常怪異。本節將介紹數種你可能會遇到的關係，使用筆者所稱 之為關係陳列館(Rogues Gallery of Relation)的工具。

16. A Rogues Gallery of Relations(淘氣鬼關係陳列館) The mapping can be viewed as a graph To see why you need to understand relations, imagine controlling the system shown in Figure 4.3. It's about as simple as a system can get, with just a single component, a single input, and a single output. The values of the input and the output both range from 0 to 100. The input has a knob and the output has a gauge, so you have complete control of the system's input and full knowledge of its output. The component itself could have any degree of internal complexity, but we'll treat it as a "black box"—all that matters is The relationship between the input and the output. One possible relationship is shown graphically in the bottom of the figure. As you turn the knob from 0 to 100, the output goes from 20 to 80. With a bit of practice, you could quickly adapt to this control and produce any available output on demand. Over time, it would become as automatic as using the gas pedal in your car. 關聯性可以用圖來表達 欲知我們為何需要瞭解關係，試想像我們正在控制圖4.3所示的系統。這是一個最 簡單不過的系統，包含一個元件(single component)、單一投入(single input)和單一 產出(single output)。產出值與投入值的範圍介於0到l00之間。投入有一個轉鈕而 且產出有一個量表，所以你對系統的投入有完全的控制權，並對產出值有完整的 知識。元件本身可以具備內部複雜性的任何程度，不過我們將以一個「黑盒子」 (black box)看待它──最重要的是投入與產出之間的關係。一種可能的關係顯示 在圖4.3的下方。當你從0到100轉動轉鈕時，產出就會從20上升到80。只要稍加練 習，你就可以很快適應這項控制，並依需求製成產出。經過一些時間，它就會像 使用汽車的油門一樣自然。

17. A Rogues Gallery of Relations(淘氣鬼關係陳列館) The mapping can be viewed as a graph The Simplest System

18. A Rogues Gallery of Relations(淘氣鬼關係陳列館) Relations come in many forms This system is easy to understand and operate because the Relation between the input and output is so simple. Unfortunately, relations in real-world systems are rarely this simple. To see some other relations that might have been lurking in this system, take a look at the relations shown in Figure 4.4. Each panel illustrates a particular kind of relation, together with the name most commonly used for that type. All of these relations are found in supply chain systems, and knowing which one you are dealing with when you are changing an input is essential to achieving good control. As you proceed from left to right in the diagram, the relations become increasingly difficult to understand and control, which is why I call them rogues. A brief rundown on each rogue will help you recognize it and deal with it successfully. 關係有多種型態 這個系統非常容易瞭解和操作，因為投入與產出的關係是如此地簡單。不 幸地，在真實世界裡關係很少是如此簡單的。要瞭解還有哪些關係可能潛 藏在這個系統裡，請看看圖4.4所呈現的不同關係類型。每一面板顯示一 種特殊的關係，並註明它最常被使用的名稱。所有關係類型都可以在供應 鏈系統裡發現，當你改變一項投入時，你需要知道你所面對的是哪一種關 係，方能達成好的控制。就你從圖的左邊往右邊移動時，關係將愈來愈難 瞭解與控制，這是為何筆者稱它們為一群淘氣鬼(rogues)的原因。接著， 我們將一一介紹每一種關係類型，以幫助你更認識它們並可成功地面對它 們。

19. A Rogues Gallery of Relations(淘氣鬼關係陳列館) Relations come in many forms The Rogues Gallery Of Relations

20. A Rogues Gallery of Relations(淘氣鬼關係陳列館) Linear relations are straight lines The relation shown in Panel A of the gallery is called a linear relation because the mapping of inputs to outputs is described by a straight line. This is the relation seen in Figure 4.3, and it isn't really a rogue at all; it has every desirable quality, and it is the best-behaved relation you could possibly hope for. Linear relations are easy to understand, easy to predict, and—best of all—easy to control because increasing the input by a constant amount always produces the same, constant increase in the output. The world would be a much more orderly place if all relations were of this clean, linear variety. Unfortunately linear relations are just one special case. All the other rogues in the gallery are decidedly nonlinear. 線性關係可以直線圖表達 上列陳列館中，A面板所顯示的關係被稱為是線性關係(linear relation)，因 為投入跟產出的關聯性可以直線關係描述。這是圖4.3所顯示的關係，它 一點也不是淘氣鬼；它具備所有我們所希望擁有的品質，它是我們可以期 許的最佳行為表現。線性關係很容易瞭解、容易預測，更好的是──容易 控制，因為增加一固定數量的投入總會獲得相同且固定數量的產出。假如 所有關係都是這種清楚與線性的類型，那世界將是一個更有秩序的地方。 不幸地，線性關係只是一個特殊例子。陳列館的所有其他關係都是非線性 的。

21. A Rogues Gallery of Relations(淘氣鬼關係陳列館) Monotonic relations always go up The monotonic relation in Panel B of the gallery is not as well behaved. The only restriction on this relation is that increasing the input never reduces the output. Beyond this, there are no guarantees regarding the shape of the curve. It could rise slowly, then plateau for a while, then shoot up steeply, and so on. This makes It much harder to use the knob to control the output because a small adjustment in the knob could produce a big change in the output in one part of the range and little or no change in another. The sample curve shown in Panel B illustrates a system that is much more sensitive in the middle of its range than it is near the ends. The effect of repetition on brand recognition often exhibits this kind of relation, showing little or no increase until a certain threshold is reached, then rising quickly to a saturation point. 單調關係朝單一方向變化 在陳列館裡的面板B屬單調關係(monotonic relation)，其行為就比較不規 範。這個關係的唯一限制，是只要增加投入量就絕不會降低產出量。除此 之外，關於這條曲線的形狀則無法保證。它可能緩慢上升，然後進入平原 期一段時間，接著突然急劇上升等等可能情況。這將使得採用轉鈕來控制 產出比較困難，因為轉紐一個小小的調整可能在某些區間帶來產出很大的 改變，而在其他區間則只有一點點或甚至沒有任何改變。圖4.4中，面板B 顯示的曲線說明該系統在中間區間比靠近兩端區間更加敏感。品牌認知重 複之效果(theEffect of repetition on brand recognition)經常顯現出這類關 係，在品牌認知未達到一個門檻值(threshold)時，顯示銷售數量很小或毫 無增加，一旦超過門檻值就快速上升到一個飽和點。

22. A Rogues Gallery of Relations(淘氣鬼關係陳列館) Continuous relations change smoothly The continuous relation illustrated in Panel C is even less well behaved; the only guarantee with this relation is that the output will rise or fall smoothly with changes in the input, without any sudden jumps. But the actual mapping can take on any form whatever. Continuous relations make control harder still because increasing the input can drive the output higher, push it lower, or leave it unchanged. Unless you have some pretty good insights into how a system works, about the best you can do with this relation is sweep the knob back and forth and watch the gauge, trying to find the spot that gives you the best output. Many companies find themselves doing this in trying to manage the relation between price and profit, which usually follows a curve like the one shown in Panel C. Up to a certain point, raising prices increases revenue and profits go up. Beyond that point, further increases result in lost sales and profits start to go back down. Finding the price that produces the largest profits is rarely an easy process. 連繽關係呈現平順的變化 面板C顯示的連續關係(continuous relation)甚至更不貝規範性；這關係唯一 的保證是產出會隨著投入的改變連續地上升或下降，不會有任何突然的增 減。但是產出轉換值卻有多種可能的結果。連續關係使控制更為困難，因 為投入的增加可能驅動產出的提高、降低，或根本毫無改變。除非你對系 統如何運作具有很好的洞察力，在這關係中你所能盡的最大努力只有來回 移動轉鈕並看著量表，設法找出可以給你最佳產出的那一點。許多公司發 現，在管理價格與利潤之間的關係時，經常像在處理面板C所顯示的曲線 一般。到某一頂點前，提高價格將增加收入與利潤。越過那一點，任何的 價格增加都將造成銷售損失，且利潤開始下滑。找出可以讓利潤最大化 的價格通常不是一件容易的程序。

23. A Rogues Gallery of Relations(淘氣鬼關係陳列館) Single-valued relations change abruptly The single-valued relation shown in Panel D is still harder to work with because even the smallest change in input can produce a Huge leap in the output, with no smooth transition between successive levels. The only thing you can count on with this relation is that it will always produce the same output for any given input. Beyond that, anything goes. This rogue is quite common in supply chains, and it's almost always a monster of our own creation. For example, quantity discounts introduce discontinuities in the relation between price and quantity, so that increasing the quantity by a single item can cause an abrupt change in price for all the items in an order, possibly even reducing the total cost rather than increasing it as expected. This kind of behavior may not seem so bad simply because it's familiar, but quantity discounts are among the practices that make supply chains hard to predict and control. 單一價值關係呈現巨幅的變化 顯示在面板D的單一價值關係(single-valued relation)仍然是不易於操控， 因為即便是投入值的一個小改變就會產生產出值的很大改變，無法在曲線 鄰近兩階(successive levels)之間平順的轉換。對此關係你唯一可以指望的 是，任何給定投入值將得到相同的產出值。除此之外，任何情況都可能發 生。在供應鏈中這類關係相當常見，它經常是企業自己所創造的怪獸。例 如，數量折扣將帶來價格與數量之間的不連續性關係，以致於單一品項所 增加的數量可能引起一個訂單內所有品項價格的突然改變，甚至可能降低 總成本而不是如預期般有所增加。這種行為大家可能覺得沒什麼，因為它 實在太平常了；不過數量折扣是造成供應鏈難以預測與控制的多種實務中 的一種做法。

24. A Rogues Gallery of Relations(淘氣鬼關係陳列館) Multi-valued relations can do anything The multi-valued relation illustrated in Panel E is the worst of rogues because it doesn't even promise to give you the same output for a given input. With this relation, a small change to the input can not only produce a sudden leap, it can shift the relation over to another curve altogether, so that reversing the change doesn't put things back the way they were. This relation may seem so perverse that it should never be permitted in supply chains, but it's there whether we like it or not. In fact, the example curve shown in Panel E is a naturally occurring pattern in the demand for fashion-based products, as explained in Chapter 10. 多重價值關係可以有任何可能的變化 面板E顯示的多重價值關係(multi-valued relation)是表現最糟糕的一種關 係，因為它甚至無法承諾在已知投入值下給你相同的產出值。在這個關係 中，投入值的一個小改變不僅會產生一個大改變，甚至可能將關係整個轉 移到另外一條曲線上，以致於將關係倒轉回原狀，並無法歸回到原始的關 係狀態。這種關係似乎是太反常了，不應該容許在供應鏈上發生，不過它 就是存在，不管你是否喜歡它。事實上，面板E所呈現的範例曲線，是流 行類產品需求的一種自然呈現。第10章將有更多解釋。

25. A Rogues Gallery of Relations(淘氣鬼關係陳列館) We are biased toward linear relations Research on human thinking and decision making reveals that we have a great deal of trouble with the rogues described above. Simply put, we naturally assume that all systems are linear in nature, and we are very bad at detecting and understanding any other kind of relation. Nonlinear relationships are quite common in supply chains, so you will have to overcome your natural inclinations if you want to master supply chain management. I will help you with this throughout the book by pointing out nonlinear relationships whenever they appear, and by showing some of the ways in which the assumption of linearity is built into our thinking about supply chains. 我們對線性關係其有偏好 對於人類思考和決策的研究顯現出，我們在面對上述不同關係類型時會產 生很大的困擾。簡單地說，我們很自然地認為，所有系統在本質上是線性 的，我們非常不善於察覺與瞭解任何其他類型的關係。非線性關係在供應 鏈上是相當普遍的，假如你希望精通供應鏈管理的話，你必須克服自我本 質上的傾向。在此方面，筆者將會在本書中提供你指引，指出非線性關係 出現的時機，並指出哪些方式會影響我們對供應鏈作線性假設的思考。

26. The Dynamics of Delay(延遲動態學) Combinations produce new kinds of behavior The range of behavior that can be observed with just a single component barely hints at what can happen when two or more components are combined. Even the simplest combinations can produce behavior that is surprising and, for the purpose of understanding supply chains, quite revealing. Figure 4.5 shows three components hooked together to form a chain, with the output of each becoming the input of the next. The components don't actually do anything; as the relations below each component indicate, they just pass their inputs through to their outputs without changing them in any way This system behaves identically to the single- component system explored in the preceding section (see Figure 4.3); the sequence of values generated by the knob—a sequence that is often called the signal—is immediately placed on the final output, just as it is in the simpler system. 組合產生了新的行為類型 從單一元件所觀察到的行為範圍，幾乎無法提供當兩個或兩個以上元件組合 時所將發生行為的任何啟示。即使最簡單的組合都可能產生令人驚訝的行為 變化，並且為了瞭解供應鏈的目的，這些簡單組合所產生的行為影響是相當 具有啟發性的。圖4.5顯示出三個元件連在一起形成一條供應鏈，每一元件的 產出成為下一元件的投入。元件事實上沒有什麼作用；誠如下圖每一元件的 關係所示，他們只是接收投入並原封不動地轉成產出。這個系統與前一節介 紹的單一元件系統的行為是完全一樣的(見圖4.3)；轉鈕所產生的一連串數值 ──這串數值常被稱為訊號(signal) ──很快地被移轉到最後的產出，正如同 在一個較簡單的系統中一般。

27. The Dynamics of Delay(延遲動態學) Combinations produce new kinds of behavior Combining Components

28. The Dynamics of Delay(延遲動態學) Delays take components out of phase It only takes a tiny alteration to make this system behave differently from the simpler one: a small delay from the time a component receives a change in its input to the time that change is reflected in its output. Figure 4.6 illustrates the impact of this delay by plotting the inputs to the three components over time. The original signal, labeled A in the figure, is faithfully replicated by the other two components, but the levels at the three components are no longer the same at any given time. In technical terms, the components are now said to be out of phase with each other. All systems involve some delays, so it is normal for their components to be out of phase. In supply chains, delays occur in all three flows—demand, supply, and cash—and they can range anywhere from minutes to months. 延遲造成元件間的時相失衡 只要有一個微小改變就會使此系統表現出與簡單系統不同的行為：從一個 元件之投入產生改變而帶來一些延遲(delay)的時間算起，到這個改變反映 在產出的時間為止。圖4.6繪製出三個元件之投入隨時間變化的曲線，說 明了這個延遲所帶來的影響。原始訊號──圖中標示為A的曲線，由其他 兩個元件完全地複製，但是這三個元件的水準在任何時點已經不再是相同 的了。以專業術語來說，這三個元件的時相(phase)已經失去平衡了。所有 系統都牽涉到一些延遲，所以元件間的時相失衡(out of phase)是常見的現 象。在供應鏈中，延遲發生在所有的三個流程──需求、供應和帳款── 延遲的範圍從幾分鐘到幾個月都有可能。

29. The Dynamics of Delay(延遲動態學) Delays take components out of phase The Effects Of Delay

30. The Dynamics of Delay(延遲動態學) Phase shifts cause havoc in supply chains To see what kind of confusion these phase shifts can cause in a supply chain, imagine that Components A, B, and C are a retailer, producer, and supplier, respectively, and that the signal of interest is the level of demand being experienced by the chain. At the time labeled t in Figure 4.6, demand at the producer is right on the average value, but demand at the retailer is below average, and the supplier is experiencing unusually high demand. Based on the most current data, each company might reach totally different conclusions about how the chain ought to be responding to current demand. If any company tries to make a correction on its own, it is almost certain to throw the other two out of balance. 元件間的時相轉變帶來供應鏈的混亂 欲瞭解這類時相轉變(phase shifts)對供應鏈可能帶來哪些困擾，且假想元 件A、B和C分別是零售商、生產商與供應商，我們 (供應鏈經理)感興趣的 訊號是供應鏈所經歷的需求水準。在圖4.6標籤為 t 的時間下，生產商的 需求落在平均值水準，但零售商的需求則低於平均值；而供應商卻感受到 不尋常的高需求。所以根據圖中的資料顯示，每一公司對於供應鏈應該如 何反映當前需求可能會得出完全不同的結論。假如任何公司設法自己去做 改善，幾乎可以肯定的是，其他兩家將會因此失去平衡。

31. The Dynamics of Delay(延遲動態學) Phase shifts are usually invisible If phase shifts were always as obvious as the ones shown in Fig-ure 4.6, they could be detected and handled rather easily But real world supply chains are never this kind. Even if the original signal is transmitted faithfully all the way up the chain, the amount of the delay introduced by each component varies both within and across components. It takes very little variation of this sort to turn the neat curves of Figure 4.6 into wild, unpredictable swings. A further complication is that the original demand signal never varies in the smooth, cyclical manner shown in the figure; it usually carves out a jagged pattern that has little or no hint of regularity (see Chapter 10). The result: Phase shifts are rarely apparent even in the best of circumstances. All that the members of the chain know is that they are experiencing different levels of demand, and there may be no way to know whether those are simple delay effects or real dis- agreements that are cause for concern. 時相轉變通常是無形的 假如時相轉變總是如圖4.6所顯示的那般明顯，它們可能相當容易察覺與掌 握。但真實世界的供應鏈從未有這種狀況。即使是原始訊號忠實地傳送到供 應鏈最上游，每一元件產生的延遲時間在元件內部與元件之間都不一樣，只 需要微小的變異就可以將圖4.6的平滑曲線轉變為狂野且無法預測的波動。更 深層的複雜性在於原始需求訊號的變化，從未如圖中所顯示般的那麼平順與 貝週期性；它通常會以毫無規則性的鋸齒狀型態出現(參考第10章之說明)。 結果是：時相轉變很少是非常明顯的，即使是在最佳的狀況之下。供應鏈成 員所瞭解的就是他們經歷了不同的需求水準，而且可能沒有辦法獲知究竟這 些狀況是起因於簡單的延遲效果，或應給予更多關注的不協調問題。

32. The Dynamics of Delay(延遲動態學) Distortions introduce further complications As puzzling as the effects of delay might be, much more confusion is introduced if there is any distortion of the signal from one component to the next. Real-world systems often show a pattern of increasing distortion as signals travel upstream, wreaking havoc among upstream components. Have you ever wondered why dense freeway traffic lurches along in waves of acceleration and braking rather than just flowing at a single, slow rate? Traffic studies have revealed that these waves can be triggered by just one or two drivers overreacting to the cars in front of them, triggering a ripple of exaggerated responses that spreads and amplifies for many miles behind them. 扭曲帶來更大的複雜度 雖然延遲效應已夠讓人困惑，但更多困惑將會因為元件間的傳遞訊號有所 扭曲(distortion)而產生。真實世界的系統經常發現訊號愈往上游移動，扭 曲程度愈加大的現象，造成上游元件之間的大混亂。你是否曾經好奇過， 為何密集的高速公路上，交通流量是在加速跟煞車的車浪之間蹦蹦前進， 而不是一種單一且緩慢的車流呢？交通流量研究顯露出，只要有一、兩個 駕駛對前方車輛過度反應，車流波動就會產生，並帶來後方綿延數哩的連 鎖性誇大反應。

33. The Dynamics of Delay(延遲動態學) Economies of scale distort signals Distortions of incoming signals can come from any number of sources, and they can be introduced accidentally or intentionally. In supply chains, the familiar economies of scale represent a common source of distortion: Customers order more than they need in order to get a quantity discount, producers run larger batches than necessary to reduce unit costs, and so on. Such decisions may save money in immediate operations, but the distortions they cause in the signals for demand, supply, and cash extract a much higher cost than most companies realize. 規模經濟扭曲了訊號 接收到的訊號被扭曲之原因可能來自於許多來源，或許是因為一些意外狀 況或是一些故意的行為。在供應鏈裡，大家所熟知的規模經濟(economies of scale)即是扭曲產生的一個共同來源：客戶為得到數量折扣訂購超過他 們所需的數量、生產商為了降低單位成本生產超過所需數量的批量等等。 這類決策可能在直接營運上節省一些成本，但是它們在需求、供應及帳款 上造成的扭曲，所帶來成本的消耗遠超過一般公司之認知。

34. The Dynamics of Delay(延遲動態學) Demand amplification is one result To see the problem in action, imagine that each component in the chain shown\ in Figure 4.5 increases the signal it receives by 50. The result would be larger and larger swings of the signal as it moves up the chain, as shown in Figure 4.7. This is precisely what happens in the phenomenon of demand amplification described in Chapter 2. The bullwhip effect that caused the wild swings in the supply chain for Pampers wasn't a strange aberration of this particular chain, but a natural outcome of traditional practices found in all supply chains. Put another way, demand amplification is a problem of our own creation, one we have woven into the very fabric of supply chain practices. The only sure way to get rid of the problem is to eliminate the practices that cause it (see Chapter 13). 需求虛增效應是其中一個結 欲瞭解問題之所在，假想圖4.5供應鏈中所顯示的每一元件加強50%收到 訊號的強度。結果將如圖4.7所示，訊號愈往上游移動，其波動幅度將愈 大。這就是我們在第2章描述的需求虛增效應(demand amplification)。造成 幫寶適紙尿褲供應鏈狂亂波動的長鞭效應，不是此供應鏈中的特異現象， 而是所有供應鏈中傳統作業模式造成的一個自然結果。換一種說法，需求 虛增效應是企業自己造成的問題，已深植於供應鏈實務之中。解決此問題 的唯一方法，就是去除造成此問題的實務做法(參考第13章之說明)。

35. The Dynamics of Delay(延遲動態學) Demand amplification is one result Combining Delay With Amplification

36. Feedback and Stability(回饋興穩定性) Outputs can be fed back into inputs In the systems discussed so far in this chapter, the signals all travel in the same direction, from the inputs toward the outputs.Although such systems exist, they are rare; most real-world systems have additional pathways that carry signals upstream as well, from outputs back to the inputs of earlier components (Figure 4.8). Such signals are called feedback because they feed information about the output back into the input, creating a loop in the system that wouldn't be there otherwise. Given that systems without feedback can be so hard to understand, adding a loop of this sort may seem like a perverse thing to do, but it turns out that the proper use of feedback is critical to producing useful, effective systems. 產出可以回饋到投入 到目前為止，本章所討論系統的所有訊號均漫遊在相同的方向上，從投入 朝向產出。雖然有這種系統存在，但卻是很稀少的；大部分真實系統均有 額外路徑，可以攜帶訊號逆流而上，從產出回到早先元件的投入(見圖4， 8)。這樣的訊號被稱為回饋(feedback)，因為它們將關於產出的資訊反饋 回投入，在系統中產生原本不存在的迴圈。既然知道沒有回饋訊號的系統 可能很不容易瞭解，加入這類迴圈似乎是一種反常的做法，但結果是適當 使用回饋對於產生有用且有效的系統非常重要。

37. Feedback and Stability(回饋興穩定性) Outputs can be fed back into inputs Introducing Feedback

38. Feedback and Stability(回饋興穩定性) Feedback comes in many forms Feedback can take on many forms. The most basic kind of feedback simply takes a portion of the output and mixes it in with the incoming signal, as shown in the upper link of Figure 4.8. The more common kind of feedback in supply chains, shown in the lower link, uses a separate signal that communicates information about the current output to an upstream component rather than redirecting part of the original signal. Feedback can be entirely automatic, or it can require human intervention, as it does when an operator monitors a gauge and adjusts an input knob to achieve a desired output. In supply chains, using feedback effectively involves many people working together to Analyze outputs and modify inputs. 回饋具有多種形式(in many forms) 回饋可以許多形式呈現。最基本的回饋種類是完全地採用產出的一部分跟 進來的訊號混合一起，如圖4.8中上面的回饋訊號所顯示。在供應鏈裡更 普遍的一種回饋，在圖4.8下方回饋訊號上顯示出來，是利用分開訊號 (separate signal)傳達關於目前產出資訊給上游元件，而不是更改部分原始 訊號的傳遞方向。回饋機制可以完全自動化，也可以由人工操作，如同作 業人員監視量表並調整投入轉鈕以讀取目標產出一般。在供應鏈裡，回饋 之有效運用牽涉到許多人必須一起工作來分析產出和修訂投入。

39. Feedback and Stability(回饋興穩定性) Positive feedback amplifies incoming signals The purpose of feedback is to provide information about current output to the upstream portions of a system, allowing them to tune their behavior to better regulate that output. To see how this works, imagine that the external signal going into Component A in Figure 4.8 is rising at a constant rate. Without feedback, the output will also rise at the same constant rate. However, if the output of Component B includes a feedback signal to A that causes it to amplify its response to the incoming signal, then the output of A will go up at an ever-increasing rate. This kind of feedback is called positive feedback because it amplifies the incoming signal strength. The result of positive feedback is an ever-accelerating increase in the output level, as shown in the left panel of Figure 4.9. If you have ever been at a presentation where someone turned the microphone amplifier up too high, you know exactly what happens with positive feedback—the signal just gets stronger and stronger until it overloads the system. 強化回饋將擴大接收到的訊號 回饋的目的是要提供系統上游所收到產出現況的資訊，以便調節行為並對 產出做更好的控制。接著介紹回饋運作方式。假想進入圖4.8元件A的外部 訊號，以一個固定比率在增加。如無回饋，產出將以相同的固定比率增 加。但是，假如元件B的產出提供A一個回饋訊號並造成A接收訊號的擴 大，那麼A的產出將會以持續增加的速度(ever-increasing rate)上升。這種 回饋稱為強化回饋(positive feedback)，因為它會放大接收訊號的強度。強 化回饋的結果是產出水準的不斷加速增加，如圖4.9左邊的面板所顯示。 假如你曾經歷過在報告之時，有人將麥克風擴音器轉得太高，你就能夠理 解什麼是強化回饋──訊號會愈來愈強，直到超過系統的負荷。

40. Feedback and Stability(回饋興穩定性) Negative feedback dampens signals Now imagine altering the feedback mechanism so that the output of B is used to decrease A's response to the incoming signal rather than increase it. This arrangement is called negative feedback because it dampens incoming signals. With negative feedback, each increase in the original signal has a smaller effect on the output, as shown in the right panel of Figure 4.9. This kind of feedback tends to keep a system within set bounds rather than pushing it toward extreme values. 弱化回饋抑制了訊號 現在假想我們倒轉回鑽機制，B的產出是被用於降低A對接收訊號的反應 而不是增加。這種安排被稱為弱化回饋(negative feedback)，因為它會抑制 進來的訊號。在弱化回饋中，原始訊號的每次增加將對產出造成較小的影 響，如圖4.9右邊面板所示。這種回饋型態傾向將系統保持在設定範圍內 (within set bounds)，而不會把它推向極端值(extreme values)。

41. Feedback and Stability(回饋興穩定性) Negative feedback dampens signals Now imagine altering the feedback mechanism so that the output of B is used to decrease A's response to the incoming signal rather than increase it. This arrangement is called negative feedback because it dampens incoming signals. With negative feedback, each increase in the original signal has a smaller effect on the output, as shown in the right panel of Figure 4.9. This kind of feedback tends to keep a system within set bounds rather than pushing it toward extreme values. 弱化回饋抑制了訊號 現在假想我們倒轉回鑽機制，B的產出是被用於降低A對接收訊號的反應 而不是增加。這種安排被稱為弱化回饋(negative feedback)，因為它會抑制 進來的訊號。在弱化回饋中，原始訊號的每次增加將對產出造成較小的影 響，如圖4.9右邊面板所示。這種回饋型態傾向將系統保持在設定範圍內 (within set bounds)，而不會把它推向極端值(extreme values)。

42. Feedback and Stability(回饋興穩定性) Negative feedback dampens signals Two Kinds of Feedback

43. Feedback and Stability(回饋興穩定性) Positive feedback fuels growth As the examples suggest, the two kinds of feedback have radically different effects on a system. Positive feedback encourages movement in a particular direction and acts to promote unbounded growth. For example, compound interest on a bank account feeds the interest back into the principal, causing it to generate more interest during the next period, and so on. The same principle explains the exponential growth of start-up companies, markets, populations, and the like; it only takes a little positive feedback to translate a modest rate of growth into an exponential explosion. 強化回饋加速了成長 誠如上述案例之建議，這二種回饋對一個系統將產生截然不同的效果。強 化回饋鼓勵系統產出朝一特定方向移動，並促成無限的成長。例如，銀行 帳戶的複合利率將本期利息回存本金，使下期產生更多的利息等等。同樣 原理可用於解釋新公司、新市場、新人口等呈現指數性成長的現象；只需 要一點點強化回饋，就可以將原本中等的成長速度(modest rate of growth) 轉變為指數性爆炸成長(exponential explosion)。

44. Feedback and Stability(回饋興穩定性) Negative feedback promotes stability By contrast, negative feedback limits movement in a particular direction, and it is most frequently used to promote stability in a system. A regressive tax system is an example of negative feedback because it reduces the increase in net income as gross income goes up. Negative feedback in economic systems is often expressed as the law of diminishing returns, in which each additional dollar invested in an activity produces a smaller return than the previous one. Of the two kinds of feedback, negative feedback is used much more extensively in the design of systems because of its ability to keep a system within reasonable operating bounds. 弱化回饋促進穩定性 相較之下，弱化回饋將限制系統產出朝特定方向移動，而它最常被使用於 提升系統的穩定性。累退稅率系統(a regressive tax system)是一種弱化回饋 的例子，因為隨著總所得的增加，此種稅率將會降低淨所得的增加。經濟 系統的弱化回饋常以報酬遞減的法則(law of diminishing returns)表現出 來，也就是在一項作業每一塊額外金錢的投資將產生比前一塊錢投資較少 的報酬。在這二種回饋中，弱化回饋在系統設計上受到更為廣泛的應用， 因其具備能力將系統限制在一合理的作業範圍內。

45. Feedback and Stability(回饋興穩定性) Feedback is vital to supply chain Feedback is the lifeblood of supply chains, and many of the supply chain initiatives described in Chapter 3 are designed to improve the flow of feedback up the chain. One of the advantages of vendor managed inventory, for example, is that it lets suppliers directly Monitor inventory levels in distribution centers and retail stores, giving them much earlier feedback on the flow of products and allowing them to tune their production accordingly. The use of point-of-sale systemsin the quick response program improves this feedback by pushing the flow gauge all the way out to the cash register and detecting the movement of goods the moment it occurs. 回饋對供應鏈十分重要 回饋(feedback)是供應鏈的命脈，在第3章所描述的許多供應鏈推動方案， 是設計來改善對供應鏈上游的回饋流程。例如，供應商管理存貨(VMI)的 一個優點，是讓供應商直接監控配銷中心和零售店面的存貨水準，很早就 提供他們產品流通的回饋訊息(feedback information)，使他們可以依之調 整生產計畫。在快速回應(QR)方案中，銷售時點系統(POS)的使用改善了 回饋方式，將物流量表推進到收銀機上並在商品一移動時即可偵測到移動 資訊。

46. Feedback and Stability(回饋興穩定性) All three flows benefit from feedback In addition to facilitating the flow of goods down the chain, feedback facilitates the flow of demand and cash back up the chain. In fact, the signals that make up the feedback loops of supply chains can become so interwoven that it no longer makes sense to try to tease them apart. Are the sales data flowing upstream from retailers giving feedback on the flow of goods, or are they actually providing early information (sometimes called feed forward) about the demand that will soon flow up the chain? The difference isn't worth debating; the important point is that free exchange of information across supply chains provides The feedback necessary to regulate all three flows across the chain. 三大主要流程均受益於回饋 除了促進商品往供應鏈下游流動之外，回饋也促進了需求與帳款往供應鏈 上游流動。事實上，構成供應鏈回饋迴圈(feedback1oops)的訊號已緊密地 交織在一起，嘗試去分離他們是沒有意義的。從零售商往上游回傳的銷售 資料有提供商品回饋的訊息嗎？或者事實上，它們提供的是未來將往上游 移動的需求的早期資訊(有時候稱為早期回饋(feed forward)呢？相異點不 值得爭辯；重點是供應鏈上下游資訊的自由交換，提供了管控供應鏈上三 大主要流程的必要回饋資訊。

47. Feedback and Stability(回饋興穩定性) Information is replacing inventory The great power of feedback in supply chains is that it reduces uncertainty by giving companies advance information about upcoming variations in demand and supply, allowing them to better cope with these variations. Without this advance notice, the only protection against variability in supply and demand is to hold enough inventory to handle the greatest demand and the lowest supply that are likely to occur, and inventory is a very expensive form of insurance. The insight that information can reduce the need for inventory has led to systematic efforts within many industries to replace inventory with information wherever possible. Indeed, substituting information for inventory is one of the most vital aspects of supply chain management, and techniques for achieving this goal are provided throughout this book. 資訊逐漸取代存貨 供應鏈回饋(feedback in supply chains)的偉大力量在於，它藉由預先提供需 求與供應的變異資訊給企業，而降低了不確定性，使企業能更有效地面對 這些變異(variations)。缺少這些預先的通知，在供需上對抗變異性的唯一 保護，是擁有足夠多的存貨來面對可能發生的最大需求量與最低供應量， 而存貨是一種非常昂貴的保險方式。資訊可以降低存貨需求的洞察力，已 引發出許多企業尋找所有可能以資訊替代存貨的系統性做法。誠然，以資 訊替代存貨是供應鏈管理非常重要的一個構面，而達成此目標的技術在本 書的各章中均有提供。

48. Supply Chains as Systems(供應鏈系統觀) Summary This chapter provides only the briefest glimpse of a very deep subject, but it's enough to help you manage supply chains more effectively. The most important insight is the relationship among understanding, prediction, and control: You have to understand your chain in order to predict its behavior, and your ability to predict is what allows you to gain control. In each of these core processes—understanding, prediction, and control—you manipulate inputs and monitor outputs to see what happens, and your success depends in large part on how you select the inputs and outputs you want to work with. Another key to success is being prepared to cope with input-output relations other than the well-behaved linear relation we all naturally assume to be at work.You also need to bear in mind the importance of feedback in supply chains, making sure that you keep enough information flowing across your chain that it can respond to changing conditions quickly and effectively. 本章僅提供一個非常深奧主題的最簡要回顧，但是它已足夠協助你更有效 地管理供應鏈。最重要的見解是瞭解、預測與控制三者之間的關係：你必 須瞭解你的供應鏈才可能預測它的行為，而你的預測能力是容許你取得控 制的關鍵。在每一個核心程序中──瞭解、預測與控制──你運用投入和 監控產出來瞭解發生了什麼事，你的成功大部分取決於你如何選擇所需的 投入與產出。另一項成功要素，是隨時準備面對我們自然認定表現良好的 線性投入一產出關係以外的那些不易應付的關係類型。你也需要牢記在心 供應鏈中回饋的重要性，確保供應鏈中有足夠的資訊流通，使它可以快速 且有效地回應環境的變化。