Predictive decision theory explains how humans should make decisions in practice given that they are not always perfect rational decision makers. Based on the prescriptive decision theory, this study addresses criticism of universal decision making models for supplier selections which have the notion of being used uniquely in all types of supplier choice situations. Issues raised are whether this performance is correct and how a dynamic decision-making model could create a more customized decision-making model which does not add much responsibility to the decision maker's judgment. A case study at Logosol, a small industrial company identifies by process mapping a complex supplier selection process consisting of three steps; prototype creation, null-series and production, based on test manufacturing. The supplier selection process is used as the basis for the creation of a dynamic decision making model. Dynamic decision-making models have the basic principle of learning from a decision and using that information in the next decision, which is considered useful in the business case as they not only use test manufacturing for product testing but also for collecting information about the supplier. Finally, the created dynamic decision model shows that universal decision-making models cannot be used in many complex supplier selection processes involving a plurality of steps. The model must be adapted to the company's individual process, however the identification method or some parts of the model used in this study may be used to create a dynamic decision model for other companies or organizations. / Preskriptiv beslutsteori säger hur människan borde fatta beslut i praktiken givet att de inte alltid är perfekt rationella beslutsfattare. Utifrån den preskriptiva beslutsteorin riktas i denna studie kritik mot universella beslutsmodeller för leverantörsval vilka har föreställningen om sig att användas kunna användas universellt i alla olika typer av leverantörsvalssituationer. Frågeställningar som väckts är om denna föreställning stämmer, samt hur en dynamisk beslutsmodell skulle kunna skapa en mer anpassad beslutsmodell vilken inte lägger lite mycket ansvar på beslutsfattarens omdöme. Genom en fallstudie hos Logosol ett litet industriföretag identifieras med hjälp av processkartläggning en komplex leverantörsvalsprocess innefattande tre steg; prototypskapande, nollserieskapande samt produktion utifrån testtillverkning. Fallföretagets leverantörsvalsprocess används som grund för skapande av en dynamisk beslutsmodell. Dynamiska beslutsmodeller har den grundläggande principen att medta lärdom från ett beslut in i nästa, vilket anses användbart för fallföretagets leverantörsvalsprocess då dom inte bara använder testtillverkning för test av produkt utan även för insamling av information om leverantören. Studien visar att föreställningen stämmer, den skapade dynamiska beslutsmodellen visar att universella beslutsmodeller inte är särskilt användbara i många komplexa leverantörsvalsprocesser innefattande ett flertal steg. Modellen måste anpassas för företagets individuella process, dock kan identifieringsmetoden eller vissa delar av modellen som använts i denna studie möjligtvis användas för att skapa en dynamisk beslutsmodell för andra företag eller organisationer.

Bakgrund: Valet av leverantör är ett väldigt viktigt sådant för inköpare för att säkerställa strategisk konkurrenskraft och ökade krav på hållbarhet har försvårat det ytterligare. För företag som anser sig värna om social och miljömässig hållbarhet går det inte längre att bara fokusera på leverantörer som erbjuder de billigaste priserna.                                         Syfte: Syftet med denna studie är att undersöka hur Hydroware och andra företag inom tillverkningsindustrin hade kunnat förändra sitt sätt att välja och utveckla leverantörer för att uppnå en mer hållbar verksamhet.                Metod: Studien har genomförts som en fallstudie, med en kvalitativ forskningsmetod och deduktivt angreppssätt. Datainsamlingen har gjorts genom semi-strukturerade intervjuer, både på plats samt via telefon. Resultat: Hydroware rekommenderas att först och främst implementera en tydligare process vid valet och utvecklingen av leverantör för att därefter kunna införa tydligare mått och kriterier ur hållbarhetssynpunkt. Ett supplier scorecard har även tagits fram för att underlätta för Hydroware att mäta och bedöma leverantörernas prestationer i syfte att uppnå en mer hållbar verksamhet. Modellen bidrar med ett systematisk tillvägagångssätt för att följa upp leverantörerna, men innehåller även en viss grad flexibilitet. Vikterna som kriterierna tilldelas kan justeras och kriterier kan antingen adderas eller reduceras beroende på eventuella marknadsförändringar eller ändrade prioriteringar. / Background: Supplier selection is a very important choice for buyers to ensure a strategic competitiveness and increased demands on sustainability have made that choice even harder. Companies that consider themselves safeguarding social and environmental sustainability  can no longer just focus on the suppliers that offers the lowest prices. Purpose: The purpose with this study was to investigate how Hydroware and other companies within the construction industry could change their way of selecting and developing their suppliers to achieve a more sustainable business. Methodology: The study was conducted as a case study with a qualitative research method and deductive approach. The data has been collected through semi-structured interviews, both onsite and by phone. Conclusion: Hydroware is primarily recommended to implement at clearer process regarding supplier selection and development, in order to later introduce more defined measurements and criterias regarding sustainability. A supplier scorecard has also been presented in order to simplify the measurement and evaluation of their suppliers with the purpose to achieve a more sustainable business. The model will contribute with a systematic approach to follow-up on their suppliers but also with a degree of flexibility.  Because the weights assigned to the criterias can be adjusted and the criterias can be added or reduced based on possible changes in the market or changed priorities.

A seleção de fornecedores é uma atividade extremamente importante para o desenvolvimento estratégico das organizações. Nessa atividade, vários critérios, alternativas e tomadores de decisão devem ser considerados no processo de tomada de decisão, o que pode trazer complexidade ao processo. Várias técnicas multicritérios são utilizadas para a avaliação e seleção de fornecedores; porém as técnicas baseadas na teoria fuzzy vêm sendo amplamente aplicadas devido à sua capacidade de modelar incertezas das avaliações dos tomadores de decisão. Entretanto, poucas técnicas são capazes de tratar adequadamente o processo de tomada de decisão em grupo. Desta maneira, esta dissertação de mestrado tem como objetivo estudar e comparar técnicas baseadas na teoria fuzzy para tomadas de decisão em grupo, aplicadas à seleção e avaliação de fornecedores. A proposta limita o estudo às técnicas baseadas nas representações hesitant fuzzy, intuitionistic fuzzy e suas variações intervaladas. O estudo inclui quatro fases: revisão sistemática de literatura; modelagem computacional das técnicas; aplicação das técnicas implementadas e análise dos resultados, incluindo análise comparativa entre as técnicas. A implementação das técnicas seguiu um modelo proposto de tomada de decisão em grupo, considerando as particularidades das representações fuzzy usadas. Foi realizada uma aplicação piloto na seleção de fornecedores em uma indústria de fiação têxtil. Os resultados foram analisados quanto à sua congruência, adequação para decisão em grupo, interação com o usuário, complexidade computacional e capacidade de modelar incertezas. Como resultado, observou-se que as parametrizações, hesitações, e imprecisões adicionais interferem diretamente nos resultados. Além disso, são apontadas vantagens e desvantagens da utilização das representações para os critérios de comparação analisados. / The supplier selection is an important activity that contributes for the organizations\' strategic development. In this activity, several criteria, alternatives and decision makers must be considered in the decision-making process, which can bring complexity to the process. Several multi-criteria techniques are used to evaluate and select suppliers; but techniques based on fuzzy theory have been widely applied because of their ability to model uncertainties in decision making evaluations. However, few techniques are able to adequately manage the group decision making process. In this way, this research aims to study and compare techniques based on fuzzy set theory for group decision making processes, applied to supplier selection. The proposal of this study is limited to the fuzzy representations hesitant fuzzy, intuitionistic fuzzy and their interval-valued generalization. This research\'s development includes four phases: a systematic literature review; computational modeling; application of the implemented techniques and analysis of the results, including comparative analysis of the techniques. The implementation of the techniques followed a proposed model of group decision making, considering the particularities of the fuzzy representations used. A pilot application was developed in the supplier selection problem in a textile spinning industry. The results were analyzed for their congruence, suitability for group decision, interaction with the user, computational complexity and the ability to model uncertainties. As a result, it has been observed that the parameterizations, hesitations, and the different inaccuracies directly interfere with the results. In addition, advantages and disadvantages of using the representations for the analyzed comparison criteria are pointed out.

A seleção de fornecedores tem impacto significante no custo e na qualidade de produtos manufaturados. Por isso, a seleção de fornecedores passou a ser vista como uma atividade bastante crítica para o desempenho da empresa compradora. Muitos estudos da literatura propõem o uso dos métodos multicritério fuzzy TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) e fuzzy AHP (Analytic Hierarchy Process) para apoiar a seleção de fornecedores. Contudo, não são encontrados estudos que avaliem o desempenho destes métodos quando usados neste domínio de problema. Diante desta lacuna, este estudo compara os métodos fuzzy TOPSIS (CHEN, 2000) e fuzzy AHP (CHANG, 1996) no apoio à seleção de fornecedores. Esta pesquisa utiliza uma abordagem quantitativa descritiva empírica, baseada em modelagem e simulação. Os métodos fuzzy TOPSIS e fuzzy AHP foram aplicados em um caso ilustrativo de seleção de fornecedores. O desempenho dos fornecedores e o peso dos critérios foram avaliados por um especialista de uma empresa. Modelos de simulação foram implementados usando MATLAB® e aplicados na seleção de fornecedores de uma empresa de uma cadeia de suprimentos automotiva. Cinco fornecedores foram avaliados em relação à qualidade, custo, entrega, perfil e relacionamento. O peso dos critérios e o desempenho dos fornecedores foi avaliado por meio da opinião de um especialista da empresa. Posteriormente, os métodos fuzzy TOPSIS e fuzzy AHP foram comparados em relação à capacidade de apoiar a decisão em grupo, qualificação de fornecedores, escolha final de fornecedores, situações de compra e modelagem de decisões sob incerteza. A eficiência dos métodos em relação à complexidade computacional e à interação requerida com o usuário também foi comparada. Os resultados mostraram que o fuzzy TOPSIS é mais flexível e mais adequado que o fuzzy AHP para modelar diferentes tipos de cenários de seleção de fornecedores. A realização desta discussão é sugerida por Ertugrul e Karakasoglu (2008), e é relevante para ajudar pesquisadores e gestores na escolha de abordagens efetivas para lidar com diferentes cenários de seleção de fornecedores. / Supplier selection has a significant influence on the cost, quality and delivery of products of the buying company. Therefore, supplier selection has become a very critical activity to the performance of the buying company. Several studies presented in the literature propose the use of fuzzy TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) and fuzzy AHP (Analytic Hierarchy Process) to aid the decision process of supplier selection. However, there are no comparative studies of these two methods when applied to the problem of supplier selection. Thus, this paper presents a comparative analysis of the methods fuzzy TOPSIS (Chen, 2000) and fuzzy AHP (Chang, 1996) applied to the problem of supplier selection. A descriptive quantitative approach was adopted as the research method. Algorithms of the methods fuzzy TOPSIS and fuzzy AHP were developed in Matlab© and applied to the selection of suppliers of a company in the automotive production chain. Five suppliers were evaluated regarding quality of conformance, cost, delivery, profile and relationship. The weight of the criteria and the performance of the suppliers were evaluated by specialist opinion from the studied company. The methods Fuzzy TOPSIS e Fuzzy AHP were compared in terms of ability to support the group decision, supplier qualification, final choice of suppliers, buying situations and modeling decisions under uncertainty. The efficiency of the methods with respect to computational complexity and the required user interaction was also compared. The comparative analysis shows that Fuzzy TOPSIS presents better than Fuzzy AHP performance, especially in scenarios in wich many alternatives are evaluated. Thus, Fuzzy TOPSIS is more flexible and appropriate than Fuzzy AHP to deal with supplier selection problem. This paper presents a new study, comparing the methods Fuzzy TOPSIS and Fuzzy AHP. As commented by Ertugrul and Karakasoglu (2008), a study such as this can contribute to the advance of knowledge, helping researchers and practitioners choosing more effective approaches to supplier selection.

A seleção de fornecedores é uma atividade extremamente importante para o desenvolvimento estratégico das organizações. Nessa atividade, vários critérios, alternativas e tomadores de decisão devem ser considerados no processo de tomada de decisão, o que pode trazer complexidade ao processo. Várias técnicas multicritérios são utilizadas para a avaliação e seleção de fornecedores; porém as técnicas baseadas na teoria fuzzy vêm sendo amplamente aplicadas devido à sua capacidade de modelar incertezas das avaliações dos tomadores de decisão. Entretanto, poucas técnicas são capazes de tratar adequadamente o processo de tomada de decisão em grupo. Desta maneira, esta dissertação de mestrado tem como objetivo estudar e comparar técnicas baseadas na teoria fuzzy para tomadas de decisão em grupo, aplicadas à seleção e avaliação de fornecedores. A proposta limita o estudo às técnicas baseadas nas representações hesitant fuzzy, intuitionistic fuzzy e suas variações intervaladas. O estudo inclui quatro fases: revisão sistemática de literatura; modelagem computacional das técnicas; aplicação das técnicas implementadas e análise dos resultados, incluindo análise comparativa entre as técnicas. A implementação das técnicas seguiu um modelo proposto de tomada de decisão em grupo, considerando as particularidades das representações fuzzy usadas. Foi realizada uma aplicação piloto na seleção de fornecedores em uma indústria de fiação têxtil. Os resultados foram analisados quanto à sua congruência, adequação para decisão em grupo, interação com o usuário, complexidade computacional e capacidade de modelar incertezas. Como resultado, observou-se que as parametrizações, hesitações, e imprecisões adicionais interferem diretamente nos resultados. Além disso, são apontadas vantagens e desvantagens da utilização das representações para os critérios de comparação analisados. / The supplier selection is an important activity that contributes for the organizations\' strategic development. In this activity, several criteria, alternatives and decision makers must be considered in the decision-making process, which can bring complexity to the process. Several multi-criteria techniques are used to evaluate and select suppliers; but techniques based on fuzzy theory have been widely applied because of their ability to model uncertainties in decision making evaluations. However, few techniques are able to adequately manage the group decision making process. In this way, this research aims to study and compare techniques based on fuzzy set theory for group decision making processes, applied to supplier selection. The proposal of this study is limited to the fuzzy representations hesitant fuzzy, intuitionistic fuzzy and their interval-valued generalization. This research\'s development includes four phases: a systematic literature review; computational modeling; application of the implemented techniques and analysis of the results, including comparative analysis of the techniques. The implementation of the techniques followed a proposed model of group decision making, considering the particularities of the fuzzy representations used. A pilot application was developed in the supplier selection problem in a textile spinning industry. The results were analyzed for their congruence, suitability for group decision, interaction with the user, computational complexity and the ability to model uncertainties. As a result, it has been observed that the parameterizations, hesitations, and the different inaccuracies directly interfere with the results. In addition, advantages and disadvantages of using the representations for the analyzed comparison criteria are pointed out.

A seleção de fornecedores tem impacto significante no custo e na qualidade de produtos manufaturados. Por isso, a seleção de fornecedores passou a ser vista como uma atividade bastante crítica para o desempenho da empresa compradora. Muitos estudos da literatura propõem o uso dos métodos multicritério fuzzy TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) e fuzzy AHP (Analytic Hierarchy Process) para apoiar a seleção de fornecedores. Contudo, não são encontrados estudos que avaliem o desempenho destes métodos quando usados neste domínio de problema. Diante desta lacuna, este estudo compara os métodos fuzzy TOPSIS (CHEN, 2000) e fuzzy AHP (CHANG, 1996) no apoio à seleção de fornecedores. Esta pesquisa utiliza uma abordagem quantitativa descritiva empírica, baseada em modelagem e simulação. Os métodos fuzzy TOPSIS e fuzzy AHP foram aplicados em um caso ilustrativo de seleção de fornecedores. O desempenho dos fornecedores e o peso dos critérios foram avaliados por um especialista de uma empresa. Modelos de simulação foram implementados usando MATLAB® e aplicados na seleção de fornecedores de uma empresa de uma cadeia de suprimentos automotiva. Cinco fornecedores foram avaliados em relação à qualidade, custo, entrega, perfil e relacionamento. O peso dos critérios e o desempenho dos fornecedores foi avaliado por meio da opinião de um especialista da empresa. Posteriormente, os métodos fuzzy TOPSIS e fuzzy AHP foram comparados em relação à capacidade de apoiar a decisão em grupo, qualificação de fornecedores, escolha final de fornecedores, situações de compra e modelagem de decisões sob incerteza. A eficiência dos métodos em relação à complexidade computacional e à interação requerida com o usuário também foi comparada. Os resultados mostraram que o fuzzy TOPSIS é mais flexível e mais adequado que o fuzzy AHP para modelar diferentes tipos de cenários de seleção de fornecedores. A realização desta discussão é sugerida por Ertugrul e Karakasoglu (2008), e é relevante para ajudar pesquisadores e gestores na escolha de abordagens efetivas para lidar com diferentes cenários de seleção de fornecedores. / Supplier selection has a significant influence on the cost, quality and delivery of products of the buying company. Therefore, supplier selection has become a very critical activity to the performance of the buying company. Several studies presented in the literature propose the use of fuzzy TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) and fuzzy AHP (Analytic Hierarchy Process) to aid the decision process of supplier selection. However, there are no comparative studies of these two methods when applied to the problem of supplier selection. Thus, this paper presents a comparative analysis of the methods fuzzy TOPSIS (Chen, 2000) and fuzzy AHP (Chang, 1996) applied to the problem of supplier selection. A descriptive quantitative approach was adopted as the research method. Algorithms of the methods fuzzy TOPSIS and fuzzy AHP were developed in Matlab© and applied to the selection of suppliers of a company in the automotive production chain. Five suppliers were evaluated regarding quality of conformance, cost, delivery, profile and relationship. The weight of the criteria and the performance of the suppliers were evaluated by specialist opinion from the studied company. The methods Fuzzy TOPSIS e Fuzzy AHP were compared in terms of ability to support the group decision, supplier qualification, final choice of suppliers, buying situations and modeling decisions under uncertainty. The efficiency of the methods with respect to computational complexity and the required user interaction was also compared. The comparative analysis shows that Fuzzy TOPSIS presents better than Fuzzy AHP performance, especially in scenarios in wich many alternatives are evaluated. Thus, Fuzzy TOPSIS is more flexible and appropriate than Fuzzy AHP to deal with supplier selection problem. This paper presents a new study, comparing the methods Fuzzy TOPSIS and Fuzzy AHP. As commented by Ertugrul and Karakasoglu (2008), a study such as this can contribute to the advance of knowledge, helping researchers and practitioners choosing more effective approaches to supplier selection.

Degree Project Advanced Level - Business Administration, Linnaeus Business School at Linnaeus University, Business Process and Supply Chain Management, 4FE02E, Spring 2010.   Authors: Muhammad Rizwan ul Haque, Ahmed Nawaz Shaikh, Kamonmarn Jaenglom, Zaheer Tariq Tutor: Petra Andersson   Title: Supplier Selection Process Improvement through Six-Sigma DMAIC (A case of Lafarge Pakistan Cement Limited)   Background: Cement industry is considered to be an intensive supplier base industry. Cement manufacturing involves several types of suppliers ranging from general utilities to large plant equipments. Also, supply chain performance is significant topic in many cement organisations. The supply chain department at Lafarge Pakistan Cement Limited (LPCL) wants to inspect and improve their supplier selection process. The intended objective of this inspection is two folded. First, LPCL wants to develop a competitive supplier base out of bulk suppliers available in the market that would result in competitive advantage over its competitors. Second, they want to improve their supplier selection process so that there would be low variance and exclusion of unnecessary activities that would ultimately help in achieving the cost, quality and service enhancement objectives.   Research question: How can the existing supplier selection process at Lafarge Pakistan Cement Limited (LPCL) be improved by applying Six-Sigma DMAIC?   Methodology: This thesis is a descriptive case study and was conducted with a deductive approach. Data was collected through interviews, discussions and questionnaire. The scientific credibility of this thesis was secured by using many sources, avoidance of assumptions, studying a common process and following standardized steps of supplier selection. Conclusion: The existing process of supplier selection at LPCL was defined and mapped to understand the process characteristics and capabilities. The existing process was then analysed to identify problem areas, variations and unnecessary activities. Corrective actions were recommended to deal with problem areas and an improved supplier selection process for LPCL was suggested with process coordination and control measures. Suggestions for future research: Based on the findings of this thesis, we suggest that the further research for LPCL could be done in the area of sourcing and suppliers relationship management. Sourcing; a study could examine the sourcing policy at LPCL on purchasing practises of products. It would also be interesting to focus more on this area which leads to excellent cost reduction. Using scenario method could compare and analyse regional, national and worldwide sourcing. Supplier Relationship Management; a study could investigate supplier relationship management that leads to creating a competitive advantage for LPCL through the development of supplier performance monitoring and supplier development programme. More details could continuously move towards cost reduction, increased reliability and risk mitigation, transparency of supplier costs and quality, and enhanced efficiency of sourcing process.

本研究主要目的為透過灰色區間數的概念，利用其解決小樣本不確定問題的特性，修正在模糊層級分析法 (Fuzzy Analytic Hierarchy Process, FAHP) 下專家 (評估小組) 意見回饋時的不確定因素來進行供應商評選，使專家 (評估小組) 在進行指標或構面間比較時，能夠反映最真實的意見。 研究方法以模糊層級分析法為基礎進行供應商選擇，藉由模糊數概念解決舊有分析層級程序法中主觀及不精確的問題，並透過灰色區間數的概念，利用其解決小樣本不確定問題的特性，解決在進行模糊層級分析過程時，評選人員數量少而導至意見回饋樣本數較少，難以估算的問題；或評估人員對於語意尺度認知不明確，而成意見回饋時的不精確，避免因為這些原因，造成評估結果不準確，導至決策的偏差。 透過專家 (評估小組) 針對需求擬定參考構面及構面下的指標，利用層級的結構，將其做有系統的連結，透過專家 (評估小組) 針對各構面及各構面下指標間的強弱依據的回答，依此結果進行分析層級程序法的計算，找出各構面及各構面下指標間權重，進行供應商評選。 本研究實驗設計假設情境為在MTO生產流程下，透過系統動態學建構流程模型，模擬製造商生產運作。另外再設立專家意見實驗組及對照組，藉由同組評估小組填答不同意見所得的權重，加乘模擬所產生的供應商基本資料轉換為相對強度得分，進行研究方法運算，再比對模擬產生之績效結果，驗證所選供應商績效的確是最佳，驗證本研究所提出之選商方法確實有效。 / In the environment of globalization, the cooperation between enterprises and the suppliers has changed closeness into diversity. How to look for the best supplier in the use of objectivity in order to meet the need of product becomes very important. Nowadays, every industry aims at the international and various developments. Materials that consist in a product may come from every corners of the world; in that case, we have more choices in picking the suitable copartner. However, the standard of the suppliers has a big influence in the production quality. This research based on Fuzzy Analytic Hierarchy Process (FAHP) use to supplier selection. Use fuzzy number to solve the problems about subjective and imprecise in Analytic Hierarchy Process (AHP). And solve the problem about small sample and uncertain situation, sometimes come about who can’t clearly understand the meaning about item to choice, during jury making decision by Grey Interval Numbers. This situation may bring about incorrect results and wrong decision. This research makes a case under the MTO (make-to-order) producing process by SCOR model. Build the System Dynamic process model to simulate the supplier’s production process. And there have two different questionnaires result every different item’s weight. Herewith prove using this research method to select supplier is feasible and efficacious. Based on the evaluation criteria of need, we hope that enterprises can make an objective and correct decision in choosing the appropriate supplier.

Η αξιολόγηση και επιλογή προμηθευτών αποτελεί μια απαραίτητη επιχειρησιακή λειτουργία για την επίτευξη βέλτιστων δυνατών προμηθειών. Λόγω της φύσης του προβλήματος αυτού, οι μέθοδοι Πολυκριτηριακής Ανάλυσης μπορούν να παίξουν αποφασιστικό ρόλο στην επίλυσή του. Η εργασία αυτή μελετά και παρουσιάζει τα πιο συνηθισμένα κριτήρια καθώς και τις πιο διαδεδομένες μεθόδους της Πολυκριτηριακής Ανάλυσης για την αξιολόγηση και επιλογή προμηθευτών των επιχειρήσεων. Στο πρώτο μέρος της εργασίας αυτής, παρουσιάζεται το θεωρητικό υπόβαθρο, όπου γίνεται αναφορά στις έρευνες προηγούμενων μελετητών του προβλήματος της αξιολόγησης και επιλογής προμηθευτών, ομαδοποιώντας μια σειρά από τους σημαντικότερους παράγοντες για την επιλογή προμηθευτών. Στη συνέχεια παρουσιάζονται οι πλέον χρηστικές μέθοδοι Πολυκριτηριακής Ανάλυσης στην αξιολόγηση προμηθευτών με αντίστοιχα παραδείγματα. Στο δεύτερο μέρος γίνεται εφαρμογή της μεθόδου της Αναλυτικής Διαδικασίας Ιεράρχησης (ΑΗΡ) συνδυάζοντάς την με Γραμμικό Προγραμματισμό, επί των πραγματικών δεδομένων της μικρομεσαίας επιχείρησης επεξεργασίας νερού Health Affair, για αξιολόγηση και επιλογή των προμηθευτών της. / Vendor selection and evaluation is a very important process for all kinds of firms. Due to the nature of the vendor selection problem, Multicriteria methods can play a decisive role to its solution. This work examines and presents the most commonly used criteria and the most widespread Multicriteria methods for vendor selection and evaluation. In the first part of the project, the Theoretical Framework is presented, where the work of previous researchers is mentioned, by grouping some of the most vital criteria in vendor selection process. Moreover, the most useful Multicriteria methods in vendor selection are analyzed into their corresponding examples. In the second part of the project, the method of Analytical Hierarchy Process (AHP) in combination with Linear Programming is implemented on the real data of a Greek water treatment SME.

This thesis addresses the challenges that firms are faced with when collaborating with suppliers in new product development (NPD) projects under technological uncertainty. A critical observation that is made in this context is that technologies are evolving faster, making products more complex. At the same time, firms become more specialized. Due to increased complexity and specialization, firms do not possess all the necessary technologies in-house and therefore need to collaborate with external organisations to incorporate new technology into their products. Common collaborators are suppliers who become integrated into the buying firm’s NPD project. However, finding suppliers and collaborating with suppliers in NPD can be problematic. In addition, external collaborations also impact the buying firm internally, since it often needs to coordinate its departments. The purpose of this thesis is to explore supplier involvement in NPD under technological uncertainty. Challenges in supplier selection are concerned with the issues of involving new suppliers or relying on old acquaintances, managing uncertainties, the dilemma of whether to commit to long-term relationships or to maintain flexibility, and deciding on which department that is responsible for evaluating and selecting the supplier. The present study of buyers and suppliers in NPD, shows the challenges that are involved in balancing control, reaching goal alignment, and managing transactional and relational governance. Internal challenges investigate the coordination between the R&D department and purchasing in NPD projects where suppliers are involved. The present findings may be of value for firms who engage in collaborative NPD, or for firms who aim to involve suppliers in their development of new products.