Hello, The following study guide below is for a systems Analysis and Design I co
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Hello, The following study guide below is for a systems Analysis and Design I course. This is for the final exam. Do you have a reference sheet or flash cards that would cover/explain these topics in detail? or, please provide a detailed example/explanation for each. Thank you in advance Text: whitten, Jeffrey and Lonnie Bentley. Introduction to systems Analysis and Design Methods. 7th edition. McGraw-Hll, 2007. ISBN-13: 978-0-07-305233-5 9731-30s2 9as3gn Methods. 7th edition. McGr aw-Hi11, 2007. ISBN-13:Explanation / Answer
First you have to understand what a "system" is. Basically, information systems are everywhere. Consider your local supermarket - they have a system which tracks inventory levels and reorders stock as required. They also have a system which looks after the financial side of the organisation; how much money has been made from a day of trading, staffing budgets, etc. These systems don't just include computers and software. They also include the people that use the system and procedures. So in short, an information system is a collection of hardware, software, data, human and procedural components intended to give the right data and information to the right person at the right time.
Systems Analysis refers to the process in which Analysts go through to determine how a system should operate - that is determining what functions the system should perform, whether it's feasible for the system to be developed (such as financial feasibility; do the benefits of the system outweigh the costs of developing the system?), what data is going to be collected and stored. In essence, Systems Analysis is concerned with problem solving - creating a system that will solve an organisational problem.
Systems Design is actually the third step of the SDLC - it's where the analysis designs how the system will operate. The physical components of the system are defined here which specifies how the problem at hand will be solved.
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Logical design is, "The part of the design phase of the SDLC in which all functional features of the system chosen for development in analysis are described independently of any computer platform." [1] A logical design for a network is an abstract functional specification for a telecommunications solution. A logical design lacks specific details such as technologies and standards and focuses on the needs at a general level. A logical network design can be a view of any part of a network. An entire enterprise educational network can be a composition of many logical designs. The lower level designs can be a university campus network that connects each building to the Internet, or it could be a view of the standard office telecommunications setup. The important quality of a logical design is that is communicates all needs in general terms.
Logical designs communicate with abstract concepts, such as a network, router or workstation, without specifying concrete details. A definition of abstraction that I like is, "the process of formulating general concepts by abstracting common properties of instances." [3] Another is a "general concept formed by extracting common features from specific examples." [3] Abstractions for complex systems, such as network designs are important because they simplify the problem space so humans can manage it. An example of a network abstraction is a WAN. A wide-area-network carries data between remote locations. To understand a WAN, you do not need to understand the physics behind fiber optic data communication, although WAN traffic may be carried over optical fiber, satellite, or copper wire. Someone specifying the need for a WAN connection on a logical network diagram can understand the concept of a WAN connection without understanding the detailed technical specifics behind it.
Logical designs are often described using terms from the customer's business vocabulary. Locations, processes, roles from the business domain can show up in the logical design. An important aspect of a logical network design is that it is part of the requirements set for a solution to a customer problem.
The basic idea of physical design is that it communicates "decisions about the hardware used to deliver a system." [2] A physical network design is created from a logical network design. A physical design will often expand elements found in a logical design. For instance, a WAN connection on a logical design diagram can be shown as a line between two buildings. When transformed into a physical design, that single line could expand into the connection, routers and other equipment at each end of the connection. The actual connection media might be shown on a physical design as well as manufacturers and other qualities of the network implementation.
The primary difference between logical network design and physical network design is that of iterative production of a solution from the identification of a problem. For example, when a business needs to share information in real time with remote offices, they are thinking in terms of business first and technology second. This is where identification of a problem begins, and as the problem is documented, it can be iteratively evolved from a logical solution into many possible physical designs. The logical design of a network can be re-implemented with new technology, and yet the logical design remains the same. Logical designs can span generations of technology, while a physical design is one realization of a logical design.
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The Feasibility study is an analysis of possible alternative solutions to a problem and a recommendation on the best alternative. It can decide whether a process be carried out by a new system more efficiently than the existing one. The feasibility study should examine three main areas; - market issues, - technical and organizational requirements, - financial overview. The results of this study are used to make a decision whether to proceed with the project, or table it. If it indeed leads to a project being approved, it will - before the real work of the proposed project starts - be used to ascertain the likelihood of the project's success. • A feasibility study should provide management with enough information to decide: 1. Whether the project can be done; 2. Whether the final product will benefit its intended users; 3. What are the alternatives among which a solution will be chosen (during subsequent phases)? 4. Is there a preferred alternative? Content of a feasibility study Things to be studied in the feasibility study: • The present organizational system • Stakeholders, users, policies, functions, objectives... • Problems with the present system • Inconsistencies, inadequacies in functionality, performance… • Possible solution alternatives Sticking with the current system” is always an alternative • Different business processes for solving the problems • Different levels/types of computerization for the solutions • Advantages and disadvantages of the alternatives Needs Analysis A needs analysis should be the first undertaking of a feasibility study as it clearly defines the project outline and the clients' requirements. Once these questions have been answered the person/s undertaking the feasibility study will have outlined the project needs definition. The following questions need to be asked to define the project needs definition: What is the end deliverable? What purpose will it serve? What are the environmental effects? What are the rules and regulations? What standards will we be measured against? What are the quality requirements? What is the minimal quality requirements allowed? What sustainability can we expect? What carry over work can we expect? What are the penalty clauses? How much do we need to outsource? How much do we need to insource? Types of Feasibility The feasibility study includes complete initial analysis of all related system. Therefore the study must be conducted in a manner that will reflect the operational, economic as well as technical and scheduling feasibility of the system proposal. These are the four main types of feasibility study. Operational This aspect defines the urgency of the problem and the acceptability of any solution. It shows if the system is developed, will it be used. The operational study includes peopleoriented and social issues: internal issues, such as manpower problems, labor objections, manager resistance, organizational conflicts and policies; also external issues, including social acceptability, legal aspects and government regulations. It takes in consideration whether the current work practices and procedures support a new system and social factors of how the organizational changes will affect the working lives of those affected by the system. Operational -The PIECES Framework The PIECES framework can help in identifying operational problems to be solved, and their urgency: Performance -- Does current mode of operation provide adequate throughput and response time? Information -- Does current mode provide end users and managers with timely, pertinent, accurate and usefully formatted information? Economy -- Does current mode of operation provide cost-effective information services to the business? Could there be a reduction in costs and/or an increase in benefits? Control -- Does current mode of operation offer effective controls to protect against fraud and to guarantee accuracy and security of data and information? Efficiency - Does current mode of operation make maximum use of available resources, including people, time, flow of forms,...? Services -- Does current mode of operation provide reliable service? Is it flexible and expandable? Technical The technical aspect explores—if the project feasibility is within the limits of current technology and does the technology exist at all, or if it is available within given resource constraints (i.e., budget, schedule,...). In the technical feasibility the system analyst look between the requirements of the organization, such as, (I) input device which can enter a large amount of data in the effective time (II) Output devices which can produce output in a bulk in an effective time (III) The choice of processing unit depends upon the type of processing required in the organization. The analyst will ask: • Is the proposed technology or solution practical? • Do we currently possess the necessary technology? • Do we possess the necessary technical expertise, and is the schedule reasonable? • Is relevant technology mature enough to be easily applied to our problem? Some firms like to use state-of-the-art technology, but most firms prefer to use mature and proven technology. A mature technology has a larger customer base for obtaining advice concerning problems and improvements. • Assuming that required technology is practical, is it available in the information systems shop? • If the technology is available, does it have the capacity to handle the solution. • If the technology is not available in, can it be acquired Schedule Feasibility Given his technical expertise, the analyst should determine if the project deadlines are reasonable whether constraints placed on the project schedule can be reasonably met. Some projects are initiated with specific deadlines. You need to determine whether the deadlines are mandatory or desirable. If the deadlines are desirable rather than mandatory, the analyst can propose alternative schedules. It is preferable (unless the deadline is absolutely mandatory) to deliver a properly functioning information system two months late than to deliver an error-prone, useless information system on time! Missed schedules are bad, but inadequate systems are worse! We may have the technology, but that doesn't mean we have the skills required to properly apply that technology. True, all information systems professionals can learn new technologies. However, that learning curve will impact the technical feasibility of the project, specifically, it will impact the schedule. Economic Feasibility The bottom line in many projects is economic feasibility. During the early phases of the project, economic feasibility analysis amounts to little more than judging whether the possible benefits of solving the problem are worthwhile. As soon as specific requirements and solutions have been identified, the analyst can weigh the costs and benefits of each alternative. This is called a cost-benefit analysis. Cost/Benefit Analysis The purpose of a cost/benefit analysis is to answer questions such as: • Is the project justified (because benefits outweigh costs)? • Can the project be done, within given cost constraints? • What is the minimal cost to attain a certain system? • What is the preferred alternative, among candidate solutions? Examples of things to consider: • Hardware/software selection • How to convince management to develop the new system • Selection among alternative financing arrangements (rent/lease/purchase) Difficulties -- discovering and assessing benefits and costs; they can both be intangible, hidden and/or hard to estimate, it's also hard to rank multi-criteria alternatives Examples of particular benefits: cost reductions, error reductions, increased flexibility of operation, improved operation, better (e.g., more accurate) and more timely information. Benefits may be classified into one of the following categories: • Monetary : when $-values can be calculated e.g. Increased sales through increased production. • Tangible (Quantified) : when benefits can be quantified, but $-values can't be calculated e.g. cost/error reductions, increased throughput/efficiency, increased margin on sales, more effective use of staff • Intangible: when neither of the above applies, it is difficult to quantify, but maybe more important! -- business analysts help estimate $ values. e.g., increased flexibility of operation, higher quality products/services, better customer relations, improved staff morale. The analyst report will also show how will the benefits accrue, when and over what timescale and how to identify benefits. (Benefits are identified at organizational level (operational, lower/middle/higher management) and by department (production, purchasing, sales) Costs are classified as: • Project-related costs • Development and purchasing costs: who builds the system (internally or contracted out)? software used (buy or build)? hardware (what to buy, buy/lease)? facilities (site, communications, power,...) • Installation and conversion costs: installing the system, training of personnel, file conversion,.... • Operational costs (on-going) • Maintenance: hardware (maintenance, lease, materials,...), software (maintenance fees and contracts), facilities • Personnel: operation, maintenance • For a small business that wants to introduce a PC-based information system, these cost categories translate to the following: • Project costs: purchasing (hardware, software, office furniture), customizing software, training, system installation and file conversion • On-going costs: operating the system (data entry, backups, helping users, vendors etc.), maintenance (software) and user support, hardware and software maintenance, supplies,... Determine Cash Flow • Project the costs and benefits over time, e.g. 3-5 years • Calculate Net Present Value for all future costs/benefits • determines future costs/benefits of the project in terms of today's dollar values o A dollar earned today is worth more than a (potential) dollar earned next year Do cost/benefit analysis • Calculate Return on Investment: • Allows comparison of lifetime profitability of alternative solutions. o ROI = Total Profit - Lifetime benefits - Lifetime costs Total Cost Lifetime Costs Calculate Break-Even point: • how long will it take (in years) to pay back the accrued costs: @ (Accrued Benefit > Accrued Cost) EVALUATING THE FEASIBILITY STUDY The feasibility study is germane to the determination of whether there should be any further plans: The conclusion might be, “We’ve looked at the proposal thoroughly, and have concluded that it does not profitably serve our needs in the foreseeable future.” But if the conclusions of the study are positive, it should provide you with a clear understanding of what the implementation plan entails in terms of change, cost, benefit, risk, and time. The feasibility study them serves two functions: • The study makes the case for funding the implementation project • The outputs of the study provide the inputs for the implementation plan
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An example of a functional requirement would be that a system must send a an email whenever a certain condition is met (e.g. an order is placed, a customer signs up, etc).
A related non-functional requirement for the system may be that emails should be sent with a latency of no greater than 12 hours from such an activity.
The functional requirement is describing the behavior of the system as it relates to the system's functionality. The non-functional requirement elaborates a performance characteristic of the system.
Typically non-functional requirements fall into areas such as:
A more complete list is available at Wikipedia's entry for non-functional requirements.
Non-functional requirements are sometimes defined in terms of metrics (something that can be measured about the system) to make them more tangible. Non-functional requirements may also describe aspects of the system that don't relate to it's execution, but rather to it's evolution over time (e.g. maintainability, extensibility, documentation, etc).
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