strategy

Supply Chain Redesign for Resilience using Simulation

Daniel Dumke — Mon, 13 Aug 2012 07:30:40 +0000

Today we have a look at current research regarding the improvement of resilience within a supply chain.
In their 2012 paper “Supply chain redesign for resilience using simulation” Carvalho et al. analyze supply chain resilience on the basis off a Portuguese automotive parts manufacturer.

Methodology

As indicated by the paper’s title the authors main method is a simulation study. The simulation model is based on the results of a case study. Semistructured interviews were conducted to gather the relevant data off a Portuguese automotive supply chain.

But first, the authors analyze the current literature on supply chain design and resilience (figure 1).

Figure 1: Literature Review Supply Chain Design (Carvalho et al., 2012)

Simulation model

The structure of the supply chain model is shown in figure 2. The Portuguese automaker has a capacity of over 180,000 vehicles per year and all vehicles are customized.

Figure 2: Supply Chain Structure (Carvalho et al., 2012)

Arena 9.0 in conjunction with Microsoft Excel has been used to implement the model of the supply chain.
The processes which have been identified rely on the SCOR process definitions. Figure 3 shows the simulation model flowchart.

Figure 3: Supply Chain Processes (Carvalho et al., 2012)

Supplier lead-times were estimated together with the case study participants using triangular distributions (figure 4).

Figure 4: Input Data Lead Times between Suppliers (Carvalho et al., 2012)

Performance was measured using two key performance indicators: lead-time and total cost.
Overall six scenarios were designed by the authors. One containing the base scenario without using any strategy to reduce risk, one using a redundancy-strategy, and another one implementing a flexibility-strategy. These scenarios were then duplicated to generate one group with a disruption in the material flow between supplier 2_1 and 1_1 and another group without any disruption.

Figure 5 shows the total cost performance in different scenarios. Scenarios to 4 and 6 are affected by the disruption.

Figure 5: Simulation Results in different Scenarios (Total Cost, Carvalho et al., 2012)

The authors conclude

Two strategies widely used to mitigate disturbance ad- verse effects on SCs were considered (flexibility and redundancy) and six scenarios were designed. To evaluate the different scenar- ios designed, two performance measures were defined and com- puted for each SC entity, Lead Time Ratio and Total Cost.
The results of the simulation allowed to compare SC behavior after the occurrence of the disturbance under the two SC resilience design strategies. Both strategies are effective in reducing the neg- ative effects of the disturbance on SC performance. When the flexibility strategy is applied the Total Cost of the SC is less, in comparison with the redundancy strategy and the Lead Time Ratio is better.

Conclusion

Since my own research revolved in parts around my own simulation model I have two comments on this specific implementation, but I would like to share with you:

I’ve seen this already in other papers: the description of the scenarios is really bad. For one there is no overview summarizing the key differences between each of these scenarios, furthermore the description of how these scenarios are implemented in the supply chain model lack in detail.
Another key aspect to simulation modeling is the validation off the model’s output. In this case the authors are using real input data from the case study, but there is no mention if they also compared the model’s output with the real supply chain.

The conclusion of the authors also highlights the difficulty of interpreting simulation results. What could one learn from this study? Redundancy and flexibility can be used to reduce risk?
For me this insight does not qualify as a groundbreaking revelation. At least not in 2012.

Reference:

Carvalho, H., Barroso, A.P., Machado, V.H., Azevedo, S., & Cruz-Machado, V. (2012). Supply chain redesign for resilience using simulation Computers & Industrial Engineering, 62, 329-341 DOI: 10.1016/j.cie.2011.10.003

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The Impact of Supply Chain Integration on Performance

Daniel Dumke — Mon, 30 Jan 2012 14:09:15 +0000

An ongoing debate in supply chain management is about the degree to which companies should collaborate with their supply chain partners. In business and research the concept is called supply chain integration and may also be a useful strategy for reducing certain risks. And of course it is an often used strategy in supply chain management in general
Analyzing the effect of supply chain integration on performance therefore is an important issue in SCM research.

Supply Chain Integration

In the case of this study supply chain integration (SCI) can be defined as

the degree to which a manufacturer strategically collaborates with its supply chain partners and collaboratively manages intra- and inter-organization processes. The goal is to achieve effective and efficient flows of products and services, information, money and decisions, to provide maximum value to the customer at low cost and high speed.

The authors split SCI in three dimensions: customer, supplier and internal integration.

Internal integration and external integration play different roles in the context of SCI. While internal integration recognizes that the departments and functions within a manufacturer should function as part of an integrated process, external integration recognizes the importance of establishing close, interactive relationships with customers and suppliers.

Methodology

The paper employs a survey design. Participants of the survey were manufacturing companies based in China.

Because of China’s size and economic diversity, we strategically selected five cities representing different stages of economic development.

Overall 4569 companies were contacted, 1356 questionnaires were distributed with a result of 617 usable replies.
Figure 1 shows profiles of the responding companies.

Figure 1: Company Profiles

The authors suggest the following hypothesis.

H1a. Internal integration is positively related to the operational performance of the manufacturer within a supply chain.

H1b. Internal integration is positively related to the business performance of the manufacturer within a supply chain.

H2a. Customer and supplier integration are positively related to the operational performance of the manufacturer within a supply chain, given the relationship between internal integration and operational performance.

H2b. Customer and supplier integration are positively related to the business performance of the manufacturer within a supply chain, given the relationship between internal integration and business performance.

H3a. Customer and supplier integration will moderate the relationship between internal integration and operational performance.

H3b. Customer and supplier integration will moderate the relationship between internal integration and business performance.

H4. An emergent taxonomy of manufacturers can be developed, based on their patterns of supplier, internal and customer integration.

H5a. The patterns of SCI are related to the operational performance of the manufacturer within a supply chain.

H5b. The patterns of SCI are related to the business performance of the manufacturer within a supply chain.

Results

The analysis of the survey offers several interesting results, these are the main points:

We found that most of our hypotheses were supported or partially supported, broadly indicating that SCI is related to performance.

Internal integration was directly related to both business and operational performance and that customer integration was directly related to operational performance.

Although supplier integration was not directly related to either type of performance, the interaction of supplier and customer integration was related to operational performance.

Our findings indicate that supplier integration is important to performance, but in a different way than internal and customer integration are.

Since the objective of SCI is to provide maximum value to the customer, the measurement of operational performance is necessarily customer-oriented.

Overall, the contingency approach reveals that internal integration forms the foundation upon which customer and supplier integration build. This suggests that companies should begin SCI with internal integration, laying the foundation for customer and supplier integration.

The configuration approach showed that the overall SCI construct was related to both operational and business performance.

The configuration approach also reveals that the effect of SCI is cumulative, providing significant insight for companies in implementing it.

Conclusion

The study shows that all three dimensions of supply chain integration are important for the performance of a manufacturing firm across industries. And China as the modern manufacturing hub is a great place to do research on this topic.

Reference:

Flynn, B., Huo, B., & Zhao, X. (2010). The impact of supply chain integration on performance: A contingency and configuration approach Journal of Operations Management, 28 (1), 58-71 DOI: 10.1016/j.jom.2009.06.001

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Supply Chain Flexibility in an uncertain Environment: exploratory Findings from Five Case Studies

Daniel Dumke — Mon, 07 Nov 2011 12:47:00 +0000

This is another look at flexibility strategies to reduce uncertainty in supply chains. This time from the point of view of five Chinese companies in the apparel industry.

Method

The authors use a case study to “illustrate and examine the different flexibility strategies adopted by supply chain participants as a result of different environmental uncertainties.”
The five companies cover different parts of the apparel supply chain. A garment and a fabric manufacturer (companies A and E, respectively), two trading companies (C and D) and a brand company (B). This diverse sample should enable the authors to make more general deductions from the generated data.
Figure 1 shows some relevant background information for the companies.

Figure 1: Case Study Companies (Yi et al., 2011; click to enlarge)

Results

The first questions revolved around the perceived uncertainties experienced by the participants. All companies mentioned that emergent orders, uncertainties about material cost and the aggressiveness of the competition are perceived as major uncertainties (figure 2).

Figure 2: Perceived Uncertainties by the Companies (Yi et al., 2011; click to enlarge)

Several different supply chain strategies were employed, a summary is displayed in figure 3.

Figure 3: Flexibility Strategies employed (Yi et al., 2011; click to enlarge)

The authors especially wanted to highlight the influence of different environmental aspects on the chosen strategies. No pattern emerged when analyzing which flexibility strategies are used for which uncertainties.
So next the authors examined the impact of the general level of uncertainty experienced by the companies and compared it with the supply chain flexibility level chosen.
The authors came up with a matrix (figure 4). Where they contrast SC uncertainty and flexibility. Companies D and B find themselves in the conservative corner while E, C and A employ a high level of flexibility to combat the uncertainties. From the interviews the authors also deducted the future positions of the companies A and B, which are indicated as A’ and B’.

Figure 4: Supply Chain Flexibility vs. Uncertainty (Yi et al., 2011)

Next the authors discuss their findings and reach four conclusions:

A low level of uncertainty in the supply chain leads to the adoption of a conservative flexibility strategy.
A high level of uncertainty in the supply chain leads to the adoption of an agile flexibility strategy.
An aggressive flexibility strategy can be proactively adopted through restructuring a firm’s operating system to reduce environmental uncertainties.
An aggressive flexibility strategy can be proactively adopted through creating new opportunities to improve a firm’s supply chain flexibility.

Conclusion

I like case study research, since usually you can gain some really genuine and new insights, in this case: What are other companies doing to contain uncertainty and how are they employing flexibility for that?

In this case I liked the paper a lot as well… up to the matrix. I don’t like matrices where the axes are not independent, because that’s not how you generate a matrix. Take the Growth-Share-Matrix, where you have the axis market growth and market share. The one is dependent on the market and the other on one company’s share in it. Relation to one another: Independent.
Here we have uncertainty on one axis and a strategy to reduce uncertainty on the other. So of course most companies would lie somewhere in the middle. So there is not much to learn from it. Of course there is not a one-to-one relationship, but anyway.

I had several more points to complain (number of interviews also only five, conclusions drawn are directly linked to their flawed matrix-framework and no quantitative measures to assess the flexibility and uncertainty levels).
But I still think the strategies mentioned from the interviews are still worth considering when choosing your own strategies.

Reference:

Yi, C.Y., Ngai, E.W.T., & Moon, K.-L. (2011). Supply chain flexibility in an uncertain environment: exploratory findings from five case studies Supply Chain Management: An International Journal, 16 (4), 271-283

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The Power of Flexibility for Mitigating Supply Chain Risks

Daniel Dumke — Wed, 26 Oct 2011 13:31:00 +0000

This article sheds light on the question of how much flexibility is necessary to secure the supply chain against disruption risks.
The paper reviewed today takes a closer look at three supply chain risks: supply, process and demand risks (figure 1).

Figure 1: Selected Risks for further Analysis (Tang and Tomlin, 2008)

Strategies

The authors focus on the short term agility to reduce risk and chose five strategies, which are analyzed in depth (figure 2).

Figure 2: Strategies for risk reduction using Flexibility (Tang and Tomlin, 2008)

The strategies are backed by several case studies each.
For all five strategies the authors build a different model. First stands the description of the scenario, second is the development of the model which fits the scenario and is able to deploy the strategy. The last step is the description of the results.

Supply risks

Flexibility via multiple suppliers
Multiple alternative suppliers can reduce the supply cost risks, since the company gains the flexibility to purchase from the company with the lowest prices.
The first model is based on a case by Intercon Japan and Li and Fung. One ordering company is confronted with supply cost risk. The price of the identical goods is random and can vary between $5 and $15. The authors calculate the profit for the single up to a five (optional) supplier case and conclude that profits rise with increasing number of suppliers, whereas the marginal increase declines (figure 3).

Figure 3: Profit vs. Number of Supplier to reduce Supply Cost Risks (Tang and Tomlin, 2008)

Flexibility via a flexible supply contract
Flexible supply contracts allow the ordering firm to adjust its predetermined order at short notice usually within a limited quantity range.
This model is based on a case with Canon, HP and Best Buy. Demand is random, the purchasing contracts between buyer and seller are negotiated in the beginning of a period. But the actual ordered quantity can be adjusted between u% less or more than the originally agreed quantity. Calculating the profits for increasing flexibility u% gives the results shown in figure 4.

Figure 4: Profit vs. Contract Flexibility (Tang and Tomlin, 2008)

Process risks

Flexibility via flexible manufacturing processes
Flexible manufacturing requires a plant to be adaptable to produce a multitude of different products.
In this model process flexibility is modeled by the number of products (h) which can be produced by one plant. Different forms are shown in figure 5.

Figure 5: Different Flexibility Systems (Tang and Tomlin, 2008)

The calculations shows that increased process flexibility can also increase profits in an uncertain scenario (figure 6).

Figure 6: Profit vs. Degree of Process Flexibility (Tang and Tomlin, 2008)

Demand risks

Flexibility via postponement
Further flexibility is gained by postponing product differentiation decisions until the latest possible point during the production process.
In this model two products are sold at a market, demand for them is uncertain. Postponing product differentiation (shown in figure 7). Calculating profits for two different random processes (Independent and Identically Distributed (IID) and Random Walk (RW) Model), shows that also increase in postponement leads to increasing profits (figure 8).

Figure 7: Scheme for Product Postponement (Tang and Tomlin, 2008)

Figure 8: Profit vs. Postponement Flexibility (Tang and Tomlin, 2008)

Flexibility via responsive pricing
Case studies show the value of price adaptability to steer customer demand.
In this model the company is able to postpone the pricing decision for the selling season until the time t. Up to this point in time the company is therefore able to observe demand. Timing flexibility increases as t increases. From this it can also be shown that increasing flexibility leads to better profits with uncertain demand. Figure 9 has the results.

Figure 9: Profits vs. Pricing Flexibility (Tang and Tomlin, 2008)

Conclusion

The authors took some effort to generate five different models to analyze the flexibility cases. Nonetheless, I would judge the models to be quite specific for the cases, which is good for the research, but also poses the question: Will these results hold true in any case? For any company and supply chain?
There are other results (e.g. by Tomlin und Wang, 2005, which indicate that flexibility might not be the right choice for risk averse companies, which might be better of by choosing a dedicated strategy instead)

But if you keep this caveat in mind this work is a strong proponent of flexibility as a tool to increase resilience in an uncertain environment.

Reference:

Tang, C., & Tomlin, B. (2008). The power of flexibility for mitigating supply chain risks International Journal of Production Economics, 116 (1), 12-27 DOI: 10.1016/j.ijpe.2008.07.008

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Discovering the Right Planning Approach for your Supply Chain

Daniel Dumke — Mon, 24 Oct 2011 13:51:00 +0000

Some weeks ago I wrote about Fisher’s suggestions on how to select the right supply chain for your product. But how to continue from there? How do different products affect the further planning steps needed?
So I looked for another article to fill the gap and found “Selecting the right planning approach for a product” by Kaipia and Holmström (2007) which covers different planning approaches for different products.
This review is based on the review of Fisher’s model, so make sure to read that article as well.

Methods

The authors build their planning approach on three methods:

Literature review
Development of a framework to differentiate planning approaches for different types of products based on a case company
Application of the selection framework in a case study

Figure 1: Overview Case Companies (Kaipia and Holmström, 2007; click to enlarge)

Case companies

Three case companies were examined: Vaisala, Mattel and Zara. Figure 1 exhibits the product properties and planning approaches currently used by them.

Vaisala, focusses on short lead times in the distribution network and local component buffers for supplies. Production is “to-order” with a high degree of flexibility. The strategic goal is to be responsive to customer demand.
Mattel, Inc, uses continuous, planned product changes, to keep supply and manufacturing efficient.
Zara’s system is based on fast reaction to changes in sales, in combination with a highly compressed design-to-customer process. Half of the demand can be seen as quite stable, so overall less responsiveness is necessary.

Planning approaches

The authors distill eight planning approaches from the literature, which are used as a basis for the selection of the right planning process. Included in figure 2 are the features and requirements for each planning approach.

Figure 2: Planning Approaches with Features and Requirements (Kaipia and Holmström, 2007; click to enlarge)

Selection process

Using the cases different product properties in supply and demand are analyzed and aligned with the requirements of the planning approaches. From this the authors deduce the selection process shown in figure 3.

Figure 3: Selection Process for the Right Planning Approach depending on the Product Type (Kaipia and Holmström, 2007; click to enlarge)

The authors conclude with general recommendations for the right planning approach for several OEM product types, shown in figure 4.

Figure 4: Recommendations for different Product Types (Kaipia and Holmström, 2007; click to enlarge)

Conclusion

While Fisher (1997) kept his work low-key, with only few pinpointed recommendations for specific products or companies, the authors in this article were more aggressive. There is even a strategy of last resort if everything else fails: simplify, invest and create the “planning organization”.

I did not find any errors in their logic conclusions, but of course these recommendations might be overly specific for many other case studies. What to use? I really liked the approach of listing the different planning approaches with the respective requirements and to deduce the planning process for the different product types from that, so may be this might be the common denominator which could be used for a multitude of cases.

Reference:

Kaipia, R., & Holmström, J. (2007). Selecting the right planning approach for a product Supply Chain Management: An International Journal, 12 (1), 3-13 DOI: 10.1108/13598540710724347

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Matching Product Architecture with Supply Chain Design

Daniel Dumke — Wed, 19 Oct 2011 15:31:00 +0000

This review is about a preprint article which already has been accepted for publication by the “European Journal of Operational Research”. But since there is only a limited space for articles in each issue of the journal, final publication of the article is delayed.
One could now argue in a general note that this behavior also signifies a delay of the progress of supply chain research over all, with all its negative long term effects. Furthermore, in the days of the internet journals should not limit themselves to an artificial (article) limit, but see only the sky or in this case the number of quality publications as their limit.
But in this case I was able to gain access to an early copy.

Product design & supply chain management

I already wrote several times (1, 2, 3, 4) on how product architecture and supply chain design could be integrated, so this is not really a new topic. But it also touches a more integrative approach of supply chain management.

Building from the early models, where a supply chain could easily be defined by a handful of properties, supply chain models nowadays reach a new level of complexity. One of these extensions is the integration of supply chain activities into the product development process, which is supposed to yield (if we trust case studies like IKEA) enormous benefits in every performance aspect of the supply chain and ultimately the company.In the study reviewed Nepal, Monplaisir and Famuyiwa first develop a conceptual and mathematical model to integrate the supply chain design decisions into the product development process. In a second step this model is then tested using two case studies.

Model

The authors suggest an integrated three step process: 1) selection of product architecture, 2) evaluation of potential suppliers, and 3) optimal configuration of supply chain.

The first step includes the development of a generic bill of materials (GBOM) for every possible product architecture scenario. Figure 1 shows the GBOM for an example Product X.

Figure 1: Generic Bill of Materials for an exemplary product (Nepal et al., 2011)

This product design also leads to a similar generic supply chain structure which is shown in figure 2.

Figure 2: Corresponding Generic Supply Chain for Product X (Nepal et al., 2011)

The second step focusses on the identification and evaluation of available the supply chain participants. Necessary information, like production cost, lead-time and compatibility index has to be collected.
The compatibility index itself is developed by the authors as well and contains information on the compatibility of this potential supplier regarding the structural, managerial and financial dimension. Each of the dimensions is then weighted to generate the complete index. Since the compatibility of the future suppliers is hard to judge before the product is even designed, the authors employ fuzzy logic, allowing them to use ranges for each of the compatibility indices instead of fixed numbers.

The last step aims to find the optimal supply chain configuration. This is done for each product architecture scenario by using a linear goal programming model, where total supply chain cost are minimized while maximizing the compatibility between the partners.

Case studies

There are two case studies, one on bulldozer assembly and manufacturing and the other on an automotive climate control system. I will only talk about the first case since I found it more interesting.

For the case the authors exercise the three steps mentioned above. First they design two different product architectures (integral and modular architectures; figure 3) and the corresponding generic supply chain networks (figure 4).

Figure 3: Case Study: Generic Bill of Materials for Bulldozer Manufacturing (Nepal et al., 2011; click to enlarge)

Figure 4: Case Study: Generic Supply Chain Network for Bulldozer Manufacturing (Nepal et al., 2011; click to enlarge)

Lastly, the authors collect the necessary information of the potential suppliers regarding cost, lead-time and ranges for the compatibility index for two different process options:

Two alternatives are considered for each node. If the node is a procurement stage, the first alternative represents the standard supply option (that is, the existing procurement arrangement). The second option represents a consignment option where the supplier is responsible for providing immediate delivery to the bulldozer line. Similarly, for the assembly node, the first option represents the standard manufacturing method while the second option represents an expedited alternative that corresponds to a supplier who has invested in process improvement efforts in order to decrease its supply lead-time.

After solving the model in the next step, the authors conclude:

In the majority of the bulldozer supply chain stages for a modular architectural design, option two has been selected. While it is more expensive than option one, option two has a lower production lead-time and higher compatibility ratings for all stages because its modularity increases the degree of dependency, based on relative costs of inputs, between supply chain nodes.

Compared with base results, where only supply chain costs are considered, this model delivers a solution which performs (slightly) worse in cost (+0,36%), but on the other hand has the potential to deliver a much more balanced and robust solution considering also compatibility issues.

Conclusion

I found the paper to be a great read and I cannot add anything else to the issues the authors already detected and mentioned in their own conclusion:

Risk factors are missing in the model (e.g. random service times)
Additional factors like sustainability and flexibility should be considered
It is very obvious that this is again a supply oriented model, so it would be great to see how distribution network decisions behave when including product design decisions (since the customers might also change depending on the product design decisions)

Reference:

Nepal, B., Monplaisir, L., & Famuyiwa, O. (2011). Matching Product Architecture with Supply Chain Design European Journal of Operational Research : 10.1016/j.ejor.2011.07.041

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Evaluation of a Firm's Supply Chain Strategy

Daniel Dumke — Wed, 05 Oct 2011 12:10:00 +0000

Today’s paper is brand new and based on the dissertation works of Roberto Perez-Franco. It can be considered as a summary of the current state of the art in supply chain strategy and extends knowledge in the field of strategy evaluation. It can be downloaded for example from Yossi Sheffi’s homepage at the MIT.

Foundation

The authors founded the following findings on two action research project with Saflex and a health care company. Several dozen interviews were conducted on different levels within the companies.

For the further research the authors define the major terms used: supply chain strategy and the difference between the supply chain and the supply chain strategy:

For the purpose of this paper, the supply chain strategy of a firm is understood as the set of ideas behind the activities, decisions and choices of that firm‟s supply chain, which serve as logical bridge between the supply chain operations in the field and the business strategy.

The difference between a supply chain and a supply chain strategy is the difference between a set of physical entities and a set of ideas. So, for example, when AMR Research publishes its “Supply Chain Top 25” list, what they are ranking are supply chains, not supply chain strategies.

Functional Strategy Map (FSM)

The authors introduce a Functional Strategy Map which “is a conceptual representation of the supply chain strategy as a bridge between operations and business strategy”. Three layers are aggregated in the FSM: strategic, functional and operational (figure 1).

Figure 1: Elements of a Functional Strategy Map (Perez-Franco et al., 2011)

A company’s supply chain is then evaluated based on the this concept using the criteria mentioned below.

A example of the FSM might look like that from Saflex in figure 2.

Figure 2: Example of a Functional Strategy Map (Perez-Franco et al., 2011; click to enlarge)

Evaluation criteria

The evaluation criteria were agreed upon before the first action research, but were adapted due to the new findings from the first and second action research.

The final suggested criteria are:

“Support: activities should support the goals of the supply chain strategy”

“Consistency: components of the supply chain strategy should be compatible”

“Coverage: the supply chain strategy should address all important areas”

“Sufficiency: the goals should be fully satisfied by the supply chain strategy”

Figure 3 illustrates the criteria.

Figure 3: Evaluation Criteria (Perez-Franco et al., 2011)

(1) Functional support: the functional themes are expected to support the strategic themes. (3) Strategic consistency: the strategic themes are expected to be compatible among themselves. (7) Functional coverage: the functional themes are expected to address all the areas of interest to the functions. (10) Functional sufficiency: The functional themes should be satisfied by the operational themes.

The authors also defined methods to evaluate these criteria within a company. I highlight the results of the consistency check here and refer you to the full paper if you are interested in more about the methods used here.

Figure 4: Incompatibility Matrix for the Functional Layer (Perez-Franco et al., 2011; click to enlarge)

Figure 4 shows the incompatibility matrix for the second company. Each axis contains the functional goals of the company and the percentages indicate the incompatibility between the ideas as given by the interviewees (lower means more compatible).

Thus this graph gives an good overview of strategic incompatibilities and clashes.

Conclusion

Thats already it. Of course the other criteria have to be evaluated as well and the authors have several of their questionnaires in the appendix.

The topic indeed is cutting edge, since there is not yet any literature on supply chain strategy evaluation.

Maybe the authors also already gave the reason for this lack of literature: Several studies already found that only less than 50% of the companies actually have a supply chain strategy.

But using this concept and these methods is a great way to make the supply chain strategy explicit and documented and evaluate it in the process as well!

Reference:

Perez-Franco, R., Singh, M., & Sheffi, Y. (2011). An approach to evaluate a firm’s supply chain strategy as a conceptual system International Journal of Production Economics

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Improving Performance in Food Supply Chains by Reducing Uncertainty

Daniel Dumke — Mon, 12 Sep 2011 15:51:00 +0000

Today’s article is from the late 90s, but sets a great example for research methodology in supply chain risk management. But don’t worry, I will focus on the results, since they’re very interesting as well. The objective of today’s article (Supply Chain Management in Food Chains: Improving Performance by Reducing Uncertainty) is to show strategies (here called principles) to reduce uncertainty, and at the same time show the beneficial effects of reduced uncertainty.

Methods

Three methods were deployed to ensure the validity of the results. Based on a case study (1) of a chilled salads supply chain sources of uncertainty were generated and improvement principles designed. The analysis of the case study’s processes was also used to feed into a simulation model (2) of the supply chain, which was validated using (another) pilot study (3).
The approach is shown in figure 1 and is meant to ensure that the results presented below are worth reading.

Figure 1: Research Approach (van der Vorst et al., 1998)

Results case studies

The sources of uncertainty, which were uncovered during the process analysis in the first case study, can be found in figure 2.

Figure 2: Sources of Uncertainty and Improvement Strategies (click to enlarge; van der Vorst et al., 1998)

For the pilot study not all of the above mentioned improvement principles have been employed. The authors evaluated the following strategies (figure 3).

Figure 3: Improvement Strategies used at the Pilot Case Study (click to enlarge; van der Vorst et al., 1998)

By implementing them a very drastic decrease in inventory levels could be achieved (examples see figure 4). Overall results can be found in figure 5.

Figure 4: Inventory Level at the Distribution Center before and after implementing the Improvement Strategies (van der Vorst et al., 1998)

Figure 5: Results of the Pilot Study (click to enlarge; van der Vorst et al., 1998)

Results simulation

The results of the pilot study were then compared to the simulation model. Overall there seems to be a good fit between the model and the real data (figure 6).

Figure 6: Validation of the Simulation Model by comparing with Real World Data (click to enlarge; van der Vorst et al., 1998)

Further results were generated using the simulation model:

For fast moving goods optimization could be achieved by increasing the delivery frequency both to the retailer and to the DC by a certain amount. Even though the picking cost rose, inventory levels could be decreased significantly.
Implementation of a computer aided ordering system lead to an improvement of supply chain performance between 10 and 20%.

Conclusion

For the authors the simulation model is a logical extension of the prior case studies. Using it makes it possible also to test alternatives which in reality might be too expensive or even impossible to test.
Another key lesson: Reduction of uncertainties again is a major driver of supply chain performance and therefore should not be neglected.

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Supply Chain Risk Management in the German Automotive Industry

Daniel Dumke — Mon, 01 Aug 2011 10:01:00 +0000

While cleaning out some of my blog directories, I just found this article in my backup repository, I already wrote it over a year ago, but it still seems relevant. So without further ado: In their 2009 article Jörn-Henrik Thun and Daniel Hoenig from the Industrieseminar Mannheim (link only in German), present their research on Supply Chain Risk Management within the German automotive industry. Their goal was twofold: a) to identify supply chain risks and risk drivers, b) investigate measures for dealing with SC risks and their impact on SC performance.

Methodology

Therefore the authors conducted a survey with 67 companies from the automotive supply chains in Germany. Respondents were primarily managers in charge of supply chain management or logistics. The answers were measured using a five-point Likert scale (from “strongly disagree” to “strongly aggree”).

Results

Based on the results of the survey the following hypotheses could not be rejected and therefore can be seen as validated:

Supply chains are susceptible to supply chain risks

Complexity (eg. globalization) and efficiency (eg. outsourcing) of the supply chain are key drivers for supply chain risks

Internal supply chain risks have a higher likelihood to occur than external risks

Companies with a high degree of supply chain risk management show a higher performance than companies with a low degree

There is a difference between companies using preventive risk mitigation instruments contrary to those using reactive instruments in terms of supply chain performance

The most interesting finding in my view is that companies using preventive instruments show higher values in terms of increased flexibility, decreased stocks, reactivity, and cost reduction, whereas the group using reactive instruments shows higher average values concerning a reduction of the bullwhip effect and external disruptions resilience. And overall: companies implementing supply chain risk management strategies show higher performance values than others.

One of the hypothesis (“External SC risks have a greater impact on the SC than internal risks”) has been rejected. The authors explain this result as follows:

The […] result might be influenced by the fact that managers estimate the impact of incidents with a higher likelihood stronger since they implicitly reevaluate the impact based on its expectation value. However, the results indicate that most of the risks supply chains are confronted with arise from inside the supply chain. This indicates that managers are able to act on these risks directly.

Conclusion

Surveys are always subjective, so results from this survey might not be true for any other sample taken.

But the logic of the hypothesis might be skewed as well. The problem with correlations is that they work both ways. For example the hypothesis “Companies with a high degree of supply chain risk management show a higher performance than companies with a low degree” can also be interpreted the other way: Companies with high performance are more likely to implement risk management measures. And this is an especially interesting one, since to my knowledge it has not yet been analyzed.

Here is some more food for thought:

External risks in this sample of companies has been perceived as not more impactful than internal risks. So this might be true or it might be based on a skewed perception. What do you think? And if it’s true, does this hold true for all industries?

Performance gains are realized if we conduct supply chain risk management. What are the most effective strategies? What strategies are you following at the moment (reactive or preventive)?

Reference:

Thun, J., & Hoenig, D. (2009). An empirical analysis of supply chain risk management in the German automotive industry International Journal of Production Economics DOI: 10.1016/j.ijpe.2009.10.010

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Single or Dual Sourcing

Daniel Dumke — Mon, 04 Jul 2011 14:10:00 +0000

Today there is only one simple question: Single or dual sourcing, what strategy should be used when faced with disruption risks.

Definitions

There are four different approaches to sourcing sole, single, dual and multiple sourcing. Sole sourcing refers to a scenario where there is only one supplier in the supplier base, whereas single sourcing refers to the conscious decision to select one, single supplier out of a choice of suppliers. The dual sourcing model indicates that two suppliers are used (not necessarily at a comparable share). As the name says with multiple sourcing, multiple suppliers are selected, depending on the price or another criteria. The paper presented here focusses on single and dual sourcing only.

Model

The authors (Yu, Zeng and Zhao) make use of a mathematical model which contains a two echelon supply chain with two suppliers. One of the suppliers (main supplier) is located offshore (long lead times) and prone to disruptions, but on the other hand less expensive. The second supplier is located locally, but more expensive. Therefore there are three different sourcing alternatives: single sourcing of the main or the secondary supplier or alternatively dual sourcing with both suppliers.

Demand in the model is correlated with the price and stochastic.

Results

For each of the sourcing strategies the authors prepare and compare the profit equations. As a result the authors conclude that there are two critical disruption probabilities at the main supplier: p₁^c and p₂^c (p₁^c2^c) which build a frame for three different cases:

Case 1: the disruption probability of the main supplier is less than p₁^c then it is optimal to only source from the offshore main supplier.
Case 2: p₁^cdisruption 2^c, then it is optimal to source from both sources
Case 3: the disruption probability is larger than p₂^c, then it is optimal only to source from the reliable, local supplier.

Figure 1 shows the three cases.

Figure 1: Profit vs. Disruption Probabilities (Yu et al., 2009)

Conclusion

Of course the formulas in the model could be used to calculate the above mentioned probabilities and then compare them to the current disruption probability to decide on the optimal strategy. But this would probably lead to wrong results, since the model contains many assumptions that are probably not met in your case study. But the intension of the model is clear: To highlight that depending on the probability of a disruption it, not only can be optimal to have dual sourcing but also to completely switch to a more reliable supplier to optimize profits.

Reference:

Yu, H., Zeng, A., & Zhao, L. (2009). Single or dual sourcing: decision-making in the presence of supply chain disruption risks Omega, 37 (4), 788-800 DOI: 10.1016/j.omega.2008.05.006

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Current Evolution of Supply Chain Management

Daniel Dumke — Mon, 02 May 2011 13:17:00 +0000

One very important part of supply chain management research is the historical analysis of supply chain practices and properties over time. Just recently I published an article on the development of supply chain strategies over the course of 20 years.
Today I want to highlight a more short term, nonetheless interesting analysis done using two surveys from 2003 and 2004 on the current state and evolution of supply chain management practices.

Surveys and Foundation

The results of the first survey were published in 2003. The 2004 study was meant as a follow up. Overall 209 participants mainly from North America and Europe from more than 20 different industries took part in the survey.
A major part of the survey consists of rating the performance in different areas of supply chain management (eg. purchasing, transportation, planning, inventory management…) based on a supply chain maturity model (figure 1). The differences between the results were then analyzed.

Figure 1: Supply Chain Maturity Model (Poirier and Quinn, 2004)

Results

There is some identifiable progress between the two years in terms of the maturity level. Figure 2 shows the results of the self assessment for 2004. The authors state that especially the high tech sector and retail show a high percentage of level 4 and 5 companies. Comparing 2003 with 2004 the results suggest a forward movement in all key areas except for the supply chain software and technology bit.

Figure 2: Results Maturity Level in Supply Chain Functions (Poirier and Quinn, 2004)

Another part of the surveys was the strategy development within the companies. The authors conclude that

overall strategy development continues to be a weak spot among the responding companies.

Especially due to a missing link between supply chain and business strategy. In 2004, over half of the companies reported to have no supply chain strategy. Only 25% agreed that their SC strategy is integrated into the business strategy. But still, the strategies are only shared with their entire supply chain by about 15%.
The authors infer that short term cost-reduction efforts still seam to be the major focus of supply chain management. This is also confirmed by a greater focus of the companies towards supply chain initiatives on reducing cost than increasing revenues.

The authors see the following hypothesis confirmed:

Companies and industries will vary widely in terms of their evolution agains the supply chain framework
Impacts of supply chain initiatives will be significant and well-documented, particularly with regard to cost savings and revenue improvements.
Companies will adopt technology solutions before improving their related processes, thereby foreclosing on the technology’s full benefits
Inter-enterprise collaboration will be a mark of the advanced firms
Customers will be the driving force behind many supply chain initiatives

Conclusion

Long term historical supply chain research can be a key in understanding the political drivers behind supply chain development within a company. And of course improving as a result. The research presented here is a good start in this direction but should be supported by a longer term continuity.
To be honest I was surprised that this short term view even spotted significant differences, since reaching another level in this maturity model usually would take more than one year (this then again shines back on the validity of the sample). And sadly I was not able to find a follow up article from one of the last years which repeated the study.

As always with questionnaire based surveys, especially those which have to be filled without guidance by one of the researchers, the results may heavily be biased by the interviewee and his environment.

From the deduction particularly the third hypothesis (“companies will adopt technology before changing processes”) seems to be hard to confirm in a survey alone and the presented evidence looks weaker than the others.

Reference:

Poirier, C.C., & Quinn, F.J. (2004). How are we doing – A Survey of Supply Chain Progress Supply Chain Management Review, 8 (8), 24-31

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Improving Confidence to mitigate Supply Chain Risks

Daniel Dumke — Mon, 04 Apr 2011 14:28:00 +0000

Yet another paper on risk mitigation strategies. This time: How to reduce risks by improving confidence. You can find the complete paper of today in the web.

Lack of Confidence

The authors theorize that especially demand risk (volatility) has increased during the last years. With several SC concepts which are aimed to reduce the slack in the supply chain during the same period, overall risks in the SC have increased dramatically.

This leads to a lack of confidence by the managers responsible for the SC in:

Order cycle time

Current order status

Demand forecasts given

Supplier’s capability to deliver

Manufacturing capabilities

Quality of the products

Transportation reliability

Services delivered

If you are still unsure if in your supply chain the lack of confidence prevails, have a look at this list.

Outcomes of the Lack of Confidence (Christopher and Lee, 2004)

Risk Spiral

The lack of confidence can help to increase risks even further. Since according to the risk spiral, lack of confidence may lead to a increase of buffers in the supply chain to make sure that the product can still be delivered.

This on the other hand leads to longer cycle times / pipelines, which reduces the visibility even further.

Risk Spiral (Christopher and Lee, 2004)

Solution

Instead of increasing buffers the authors recommend to improve visibility and control:

Visibility

The key to improved supply chain visibility is shared information among supply chain members. Traditionally companies have tended to subscribe to the view that ‘information is power’ and to interpret the phrase as meaning power is diminished if that information is shared. In fact in supply chains the reverse is true. If information between supply chain members is shared, its power increases significantly. This is because shared information reduces uncertainty and thus reduces the need for safety stock.

Control
The goal here is to improve flexibility over the supply and own processes. The time to react to the new information gained above has to be used well.

Conclusion

Visibility and control summarizes several existing strategies (like information exchange and reducing lead times) into a new concept for thinking about supply chain risk mitigation. It therefore has the potential to lead to new / better strategies to reduce risks. The table above can be used to analyzed if some supply chain is already affected by low confidence. From a scientific standpoint I am missing the grounds for this conclusions. Obviously, this paper is not proving / supporting any theory, since it does not contain any survey or other modeling method. But on the other hand it also does not contain any hint for the method used for theory creation.

Reference:

Christopher, M., & Lee, H. (2004). Mitigating supply chain risk through improved confidence International Journal of Physical Distribution & Logistics Management, 34 (5), 388-396 DOI: 10.1108/09600030410545436

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Be prepared for the Unthinkable

Daniel Dumke — Wed, 30 Mar 2011 09:07:00 +0000

Today I just want to highlight a short article from “The Conversation” blog at the Harvard Business Review for you to read. The article, which can be found here, was written by Harold Sirkin, senior parter at the Boston Consulting Group.

Problem

Sirkin describes the problem of disruptive events referring to the black swan analogy. In hindsight most people can explain the cause and effect relations of the Japanese disaster with ease, but beforehand most companies belief that such events could not be predicted, or prepared for. Sirkin disagrees, and suggests the following measures to improve performance in extreme situations.

Measures

Preparation for the unlikely is key to lowering the impact on the own company, this includes a diversification of the supply base and a locking of supplies before shortages occur.

Companies should furthermore invest in flexibility, so producing more products locally and lower the fixed cost, eg. by outsourcing.

As you see it is a really short article…

Conclusion

Of course this is no research paper, with elaborate methodology. I see it more as a business insight, what are companies doing. Or in this case what are the current recommendations of the consultants.
For my critique I would like to make three points:
I found it rather confusing how to fill the gap between the companies which do not see themselves able to predict disruptive events and the consultant who recommends preparing for the unknown. I think what Sirkin implicitly means is that it is not about modeling specific scenarios (like the Japan earthquake) and assigning probabilities to them. But to think about more general ways to increase the resilience of the supply chain, which can be helpful for a large number of different scenarios.

Furthermore, the recommended measures miss the current trend for cost minimization and how to align both goals. I could well imaging another BCG consultant telling the same company to reduce supplier redundancy and operational flexibility to reduce cost. So perhaps risk mitigation is just not for all?

Most importantly, this article also follows the Black Swan, since it is only written in hindsight as well. As you can see from the other publications of Sirkin on the HBR, which are mostly about supply chain innovation and change management, consultants fall for the trending topics as well. This is a problem for disruptions because they usually do not happen cumulatively but with long intervals between them. So the right time for this article would have been half a year ago or one year in the future. But everybody is wiser after the fact, and forgets soon thereafter. (Since I did not do a full review of all publications of Sirkin, this conclusion may be skewed.)

Reference:

Sirkin, Harold L. (March 28, 2011 ). How to Prepare Your Supply Chain for the Unthinkable Harvard Business Review – Blogs Link: blogs.hbr.org/cs/2011/03/why_are_supply_chains_eternall.html

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Analysis of Logistics Strategies from 1990 to 2008

Daniel Dumke — Mon, 21 Mar 2011 16:02:00 +0000

Do supply chain strategies evolve over time? Are there the same strategic options nowadays compared to 20 years ago?
Since at least the meaning of the term logistics has evolved during the last 20 years, especially due to the emergence of supply chain management, logistics and supply chain management are used interchangeable in this article.

In 1987 Bowersox and Daugherty created a logistics strategy framework, concluding that there are basically three SC strategies:

Process Strategy
management of the traditional logistics activities with a primary goal of controlling costs
Market Strategy
management of selected traditional logistics activities across business units with the goal of reducing complexity faced by customers
Information Strategy
management as a system, with the goal of achieving inter-organizational coordination and collaboration through the channel.

Hypothesis

Building on this framework McGinnis, Kohn, Spillan (2010) executed and analyzed four surveys from the years 1990, 1994, 1999, 2008 with the above mentioned research questions in mind. The following hypothesis were designed:

Importance of Bowersox framework remained constant
Dependent variables (statistical data on the survey participants like: logistics coordination effectiveness, customer service commitment and competitiveness) remained constant
Within a logistics strategy, process strategy, market strategy, and information strategy will be of equal importance.

Results

First, the results show, that the dependent variables and the perception of the strategies did not change too much to make a comparison between the studies impossible.
To analyze the results further the authors clustered the respondents into three strategy clusters (intense, intermediate and passive cluster), depending on their propensity for the mentioned strategies. Here is what they found:

Intense Logistics Strategy increased
That means that either the importance of logistics strategy in U.S. manufacturing firms increased in importance or the firms were more intensely managed overall, including logistics
Relative Importance
Process strategy (cost control) is generally more important than market strategy (reducing complexity faced by customers), and that both are more important than information strategy (inter-organizational cooperation and collaboration).

The authors conclude that the Bowersox and Daugherty (1987) typology still provides an excellent framework and that strategy is more stable over time than expected. The primary focus of an intense supply chain strategy is cost efficiency and complexity reduction; furthermore it appears that cost efficiency and reduced customer complexity are facilitated by the information strategy in the intense logistics cluster.

Conclusion

I think this kind of historical analysis is much to seldom in current research. In the popular reporting very often the hypothesis is made: This topic has experienced growing attention / relevance / … But has the world really become eg. more dangerous haven’t there always been violent attacks on people and property? I think McGinnis et al. provide a great basis for this kind of discussion. The answer is: Yes, there have been to the logistics strategies used by companies in the last 20 years, but not so much though. Of course this does not make a great headline like…

Reference:

McGinnis, M.A, Kohn, J.W., & Spillan, J.E. (2010). A Longitudinal Study of Logistics Strategy: 1990-2008 Journal of Business Logistics, 31 (1), 217-235

Bowersox, D.J., & Daugherty, P.J. (1987). Emerging Patterns of Logistical Organization Journal of Business Logistics, 8 (1), 46-60

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Managing Strategic Partnerships

Daniel Dumke — Wed, 09 Mar 2011 06:57:00 +0000

Setting up the right partnerships is hard to do. There are multiple levels to the decision with which companies to setup formal relations and how deep this relationship should be? Christopher and Jüttner (2000) develop a framework for managing partnerships. The full paper can be found here.

Introduction

The authors use focus group interviews and multiple case studies to gain insights into practitioners’ experiences.
Several factors are affecting an increasing focus on partnership management: The value chain orientation, rationalization of the supplier base, growing interdependencies and growing focus on the competition of supply chains and not companies.

Framework for Strategic Partnerships (Christopher and Jüttner, 2000)

Framework

The key factors of the framework are: to define a balanced set of relationships, development of an interface structure, cooperation, change management, relationship promoters and monitoring.

Defining a balanced set of relationships
Keep in mind that partnerships are resource-intensive investments, first a company has to define its own strategy. Since the complexity of the network is dependent on number of levels, the existing relationships have to be evaluated: Can I substitute suppliers, buyers, goods? What are our common interest and what are my transaction cost? Christoper and Jüttner suggest, that this should not be done by multidimensional evaluation matrices, but a simple hierarchy to rank the suppliers / buyers may be sufficient. To generate some incentives for new comers this ranking and the generation process should be made transparent.
Developing the right interface structure
The authors argue that the quality of relationship is influenced by the closeness of the parties. There are distinctive types of interfaces which can be used for such a relationship: 1) only buyer / seller interaction (focus on price and margin, few resources invested, large number of relationships); 2) closer collaboration between buying and selling (“account management”); 3) relationship between companies, where there is direct interaction between a range of functions and usually substantial investment in the relationship
Cooperation
Here aspects like information sharing or data accuracy come into play. Also the sensitive parts of partnership are important
Change management
The authors want to point out that the change towards a company which embraces strategic relationships is not an easy one. Therefore managing people through this change is an essential part of partnership management.
Assigning a relationship promoter
To prevent relationship issues a relationship promoter on each side of the partnership is advised.
Monitoring the relationships
Monitoring can be done in a formal and / or informal way. The important point here is not to loose track of what has been achieved and how it was achieved.

Conclusion

Christopher and Jüttner provide a refreshing read on strategic partnership management. Refreshing, because they are not focussed on only one possible way eg. to measure the performance of the chain. They acknowledge that depending on the context a more informal way of measuring might be appropriate as well.

Reference:

Christopher, M., & Jüttner, U. (2000). Developing strategic partnerships in the supply chain: a practitioner perspective European Journal of Purchasing & Supply Management, 6 (2), 117-127 DOI: 10.1016/S0969-7012(99)00038-6

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