Name: : Stochastic System
Based on: System (Abstract)
Abstract System: This system has been identified as an abstract system that cannot be implemented directly. The abstract system establishes a shared pattern of characteristics that any system can use to describe its unique characteristics when referenced in the 'based on' list above. These references are described using a generalization association in UML.
The Stochastic System is a type of system where there are random elements that are part of the system. This also implies that there are probabilities associated with the variables and states of the system. See the wikipedia article:
This is a general type of system that includes noise or random variations. Examples are:
- Decision making processes in organizations
- Sensors that sample variables within a system.
- Accuracy of plans and estimates in organizations.
In the type of system, the structure of the system may be identical to a non stochastic system however, the behaviour of the system starts to exhibit random variations and wider stability swings.
The purpose for accurate reviews and audits provide for a stabilizing influence on the performance of a stochastic system.
May also be considered as a probabilistic system where the system can be described as a set of probabilities.
Systemic Measurable Variables
The measurable variables for the system-of-interest provide the means of determining performance, quality, response times, and effectiveness of change. The variable description included in this specification provides the key and top level variables for this system-of-interest. These variables provide meaning for stakeholders externally and internally. A full definition of these system variables contains the following:
- Units and definition of the scale.
- How and when the variable is measured
- Key markers on the scale: Minimum acceptable, Objective (goal), Target, Stretch, etc.
Systemic Capabilities or Functions
The capabilities of the system-of-interest or the individual functions that transform inputs to desired results are identified in this section. There may be a number of capabilities or functions this system-of-interest provides. Some of these are desired and expected and some may be undesired and unexpected.
System States
There may be a number of types of states that may be defined in this section. The various defined states that the system-of-interest can be in.
- Architectural states: These are states that align to a specific version of the Architecture Description for a system. For example, there may be:
- a Current Architecture Description,
- a number of intermediate Architecture Descriptions (representing key operational points)
- and the Target Architecture Description for a revision.
- Transformational States: These transformational states tend to align to key stages in the development process. These are typically
- Designed
- Built
- Integrated
- Released
- Operational
- Operational States: Operational States relate to the type of outcomes that are expected. Some may relate to the delivery of products and services while others relate to specific operational states and objectives. These states are identified in the capabilities and processes used during operation. These operational states are designed and implemented into the way the operational system performs.
Identify the key stakeholders and their concerns for this system-of-interest. Each stakeholder is identified and their concerns and interests are identified. The list below is an example. Each system-of-interest will have a specific set of stakeholders and concerns.
- Owner / manager: Is this a sustainable / stable system? will our customers be satisfied?
- System Architect: Are the system concepts understood? Are the system properties sufficient to deliver the objectives?
- People in the environment Will the people confirm or use the benefits of the system?
- Change Agents Do we have the ability to change the system in a planned way?
- People who are part of the system Will I understand my contribution to the system?
The following definitions are used for Environment:
- ISO 42010: 2011 and ISO 15288:2015: Environment: (system) context determining the setting and circumstances of all influences upon a system
- ISO 9000:2015: Context of the Organization: combination of internal and external issues that can have an effect on an organization’s approach to developing and achieving its objectives
The system-of-interest interacts with the environment as an open system. This section describes some of the key interactions and the relationship to the various properties of the system.
The environment and the potential impacts on the system-of-interest.
this section includes
- Transactional: This typically relates to an exchange of goods or services with a customer or user. Typically the system-of-interest may have influence without control.
- Contextual: This type of environment cannot be influenced or controlled but may have an impact on the system. This includes natural disasters, wars, etc.
- Regulatory: Regulatory requirements constrain the actions of the system-of-interest and may require specific types of interaction with external regulators.
The system-of-interest is situated in its environment as an open system. The environment that can influence the purpose and properties as a whole of the system-of-interest are identified here. These can be:
- the physical environment (weather, earthquakes, rivers, etc)
- local communities
- transportation
- the government
- competition
- education.
- etc..
For systems that can be described in a similar way to Figure 2 Page 12 of ISO 15288:2015, each of the systems identified in the hierarchy will participate as a system element and have the containing system serve as an environment. This provides a fractal model for systems within an overall system-of-interest.
Identifying the probabilities of occurrence of a range of outcomes or results resulting from stochastic processes can provide insight into the complexity of predicting the performance or stability of a Stochastic System.
So, stochastic systems would include a normal conceptual System Breakdown Structure (SBS) with identified areas of high stochastic processes potential. The behavior section would provide more information on the probability distributions of the interactions.
The interactions of the system elements are documented here. Each of the system element interactions is identified in this section and modeled. Behavioral and state models provide views of the dynamic aspects of the interaction of the system elements that creates the system properties. At a high level, the sentences that describe the interaction and relationships provide a high level specification of this interaction. Stochastic Processes will be identified along with any data or mathematical methods that have been identified. Typically any system that includes living systems will have some elements of stochastic processes.
The relationships or interactions are defined in this section. The picture included in this section shows the way the system elements interact.
In this picture, the lines between the system elements are defined. These may represent formal interfaces, such as, communication interactions, protocols, information flows, Contracts, etc. In this section, the relationships may be defined.
Configuration / Scenario:
Describes any configuration / scenario attributes for a specific system-of-interest. This may not be appropriate for all system descriptions (e.g. patterns or abstract systems).
Cyclical (Repeating / Regular) Processes
Some of the systems involved in the creation, of the system-of-interest, may need to create, change or transform system elements within the system-of-interest. These life cycles relate to the system elements that make up the system-of-interest. This also provides a structure for the various state transitions for the system-of-interest (e.g. architectural, transformational and operational).
Causal Loop Diagrams (CLD), Activity Diagrams, Markov Chains, Monte Carlo Methods, Decision trees, etc. all fit in this area.
Development Life Cycle Processes
These life cycle elements describe the overall approach to create, use and release / retire a system-of-interest. This is the normal life cycle of the system-of-interest. This section identifies the systems involved in the elements of this life cycle. These may be external systems or internal systems that create this system-of-interest
The following references support this type of system-of-interest.
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