Glen (2004) and Little (2000) list the basic facts that are important for a researcher to understand at the beginning of learning how to develop conceptual models as:
i. Development of conceptual models is first step in developing more detailed quantitative models;
ii. Interactive development of conceptual models can be used very effectively as an interactive
engagement environment;
iii. If some of the audience is unfamiliar with the development and validation of conceptual models, it helps them understand a different physical process.
iv. The development of conceptual models can help introduce the terminologies and to a conceptual understanding of systems thinking and modeling.
Table.3.1 indicates the special considerations in developing a conceptual model
Table223.1: Special Considerations for Developing a Conceptual Model
Accurate Representation of the Science or Theory Stylistic Elements for Communicating Relationships
and Emphasis
• What are the relationships among the variables
depicted?
– Independent, dependent
– Antecedents, predictor – Moderators, mediators
• Use of different shapes and object sizes; placement
• Is there an ordering of the variables (e.g. rank,
sequence or temporal)
• Use of border styles
• Use of lines (styles, sizes) to denote connectivity • Are there interactions among sets of variables? • Use of arrows (styles, sizes) for directionality
• Use of emphasized text (bold, underline, case) Source: Glen (2004)
3.6.4 Conceptual Modelling Techniques
As systems have become increasingly complex, the role of conceptual modelling has dramatically expanded. With that expanded presence the study finds that the idea by Cohen and Whang (2007) that the effectiveness of conceptual modelling at capturing the fundamentals of a system is being realized. Building on that realization, numerous conceptual modelling techniques have been created. These techniques can be applied across multiple disciplines to increase the users understanding of the system to be modelled. A few techniques are briefly described. However, many more exist or are being developed. The commonly used conceptual modelling techniques and methods include Workflow Modelling, Workforce Modelling, Rapid Application Development, Object Role Modelling, and Unified Modelling Language (UML) (Cohen and Whang, 2007).
i. Data Flow Modelling
Data flow modelling (DFM) is a basic conceptual modelling technique that graphically represents elements of a system. DFM is a fairly simple technique. However, like many conceptual modelling techniques, it is possible to construct higher and lower level representative diagrams. This argument is also advocated by Ellram (2011a) and Ellram (2011b) that the data flow diagram usually does not convey complex system details such as parallel development considerations or timing information, but rather works to bring the major system functions into context. Data flow modelling is a central technique used in systems development that utilizes the Structured Systems Analysis and Design Method (SSADM).
As described above, data flow modelling technique is used in system development which is important in SCM model as there are systems in the supply chain. This is among the focus of development of SCM Model in this study.
ii. Entity Relationship Modelling
Entity-relationship modelling (ERM) is a type of conceptual modelling technique used primarily for software system representation (Ellram, 2011a). Entity-relationship diagrams, which are a product of executing the ERM technique, are normally used to represent database models and information systems. The main components of the diagram are the entities and relationships. The entities can represent independent functions, objects, or events. The relationships are responsible for relating the entities to one another. To form a system process, the relationships are combined with the entities and any attributes needed to further describe the process. Multiple diagramming conventions exist for this technique; IDEF1X, Bachman, and
Express, to name a few. These conventions are just different ways of viewing and organizing the data to represent different system aspects. In the conceptual SCM Model, relationship among entities is very crucial and is clearly reflected. The entities are key players such as suppliers, distributers, transporters, financiers, marketers, planners and many other players in the execution of the model. Therefore, this technique is important in the development of the conceptual coffee SCM Model as it incorporates the functions of different entities of the supply chain.
iii. Event-Driven Process Chain
The event-driven process chain (EPC) is a conceptual modelling technique which is mainly used to systematically improve business process flows. Like most conceptual modelling techniques, the event driven process chain consists of entities/elements and functions that allow relationships to be developed and processed. More specifically, the EPC is made up of events which define what state a process is in or the rules by which it operates. In order to progress through events, a function/ active event must be executed (Ellram, 2011b). Depending on the process flow, the function has the ability to transform event states or link to other event driven process chains. Other elements exist within an EPC, all of which work together to define how and by what rules the system operates. The EPC technique can be applied to business practices such as resource planning, process improvement, and logistics. Taking into consideration that SCMM consists of many players with different objectives but with the intention to deliver quality product to the consumer, this kind of business must be regularly improved and should follow business rules. Thus, this technique fits the development of conceptual coffee SCMM.
iv. Joint Application Development
The Dynamic Systems Development Method (DSDM) uses a specific process called Joint Application Design (JAD) to conceptually model a systems life cycle. JAD is intended to focus more on the higher level development planning that precedes a projects initialization. The JAD process calls for a series of workshops in which the participants work to identify, define, and generally map a successful project from conception to completion. This method has been found to not work well for large scale applications, however smaller applications usually report some net gain in efficiency. As the description states in this modelling technique “the participants work to identify, define, and generally map a successful project from conception to completion” this one of the thrust of the SCM Model.
v. Place Transition Net
Also known as Petri Nets, this conceptual modelling technique allows a system to be constructed with elements that can be described by direct mathematical means. The petri net, because of its nondeterministic execution properties and well defined mathematical theory, is a useful technique for modelling concurrent system behavior, i.e. simultaneous process executions. This kind of modelling technique is not suitable for the conceptual coffee SCM model that will be developed in this study as it focuses on mathematical aspects.
vi. State Transition Modelling
State transition modelling makes use of state transition diagrams to describe system behavior. These state transition diagrams use distinct states to define system behaviour and changes. Most current modelling tools contain some kind of ability to represent state transition modelling. The use of state transition models can be most easily recognized as logic state diagrams and directed graphs for finite state machines. The conceptual coffee SCM Model to be developed under this study will not apply this modelling technique. 3.6.5 Special Considerations
Because the conceptual modelling method can sometimes be purposefully vague to account for a broad area of use, the actual application of concept modelling can become difficult. To alleviate this issue, and shed some light on what to consider when selecting an appropriate conceptual modelling technique, the framework proposed by Birou, Fawcett and Magnan (2008) are discussed in the following sections.
i. Considering Technique Evaluation and Selection
Before evaluating the effectiveness of a conceptual modelling technique for a particular application, an important concept must be understood; comparing conceptual models by way of specifically focusing on their graphical or top level representations is short-sighted. Birou, Fawcett and Magnan (2008) make a good point when arguing that the emphasis should be placed on a conceptual modelling language when choosing an appropriate technique. In general, a conceptual model is developed using some form of conceptual modelling technique. That technique will utilize a conceptual modelling language that determines the rules for how the model is arrived at. Understanding the capabilities of the specific language used is inherent to properly evaluating a conceptual modelling technique, as the language reflects the techniques descriptive ability. Also, the conceptual modelling language will directly influence the depth at
ii. Considering Affecting Factors
Building on some of their earlier work, Birou, Fawcett and Magnan (2008) acknowledge some main points to consider when studying the affecting factors: the content that the conceptual model must represent, the method in which the model will be presented, the characteristics of the models users, and the conceptual model languages specific task. The conceptual models content should be considered in order to select a technique that would allow relevant information to be presented. The presentation method for selection purposes would focus on the techniques ability to represent the model at the intended level of depth and detail. The characteristic of the models users or participants is an important aspect to consider. A participant's background and experience in the view of Ellram, (2011a) should coincide with the conceptual models complexity, else misrepresentation of the system or misunderstanding of key system concepts could lead to problems in that systems realization. The conceptual model language task will further allow an appropriate technique to be chosen. The difference between creating a system conceptual model to convey system functionality and creating a system conceptual model to interpret that functionality could involve to completely different types of conceptual modelling languages.
iii. Considering Affected Variables
Birou, Fawcett and Magnan (2008) expand the affected variable content of their proposed framework by considering the focus of observation and the criterion for comparison. The focus of observation considers whether the conceptual modelling technique will create a "new product", or whether the technique will only bring about a more intimate understanding of the system being modeled. The criterion for comparison would weigh the ability of the conceptual modelling technique to be efficient or effective. A conceptual modelling technique that allows for development of a system model which takes all system variables into account at a high level may make the process of understanding the system functionality more efficient, but the technique lacks the necessary information to explain the internal processes, rendering the model less effective.
When deciding which conceptual technique to use, the recommendations by Birou, Fawcett and Magnan (2008) can be applied in order to properly evaluate the scope of the conceptual model in question. Understanding the conceptual models scope will lead to a more informed selection of a technique that properly addresses that particular model. In summary, when deciding between modelling techniques,
answering the following questions would allow one to address some important conceptual modelling considerations.
1. What content will the conceptual model represent? 2. How will the conceptual model be presented?
3. Who will be using or participating in the conceptual model? 4. How will the conceptual model describe the system? 5. What is the conceptual models focus of observation?
6. Will the conceptual model be efficient or effective in describing the system?
Another function of the simulation conceptual model is to provide a rational and factual basis for assessment of simulation application appropriateness. Essentially, from the explanations under the whole of section 3.6, there is only one conceptual model except that there are different approaches or techniques in the modelling or development of the conceptual models depending on the activity that the modeller intends to undertake. This is so from the fact that an engineer will design a conceptual model using different technique from the economist who intends to solve a business challenge.