Systems Analysis

Year 12 Lesson

Transcript

1. SYSTEMS ANALYSIS COMPUTER SCIENCE
2. COMPUTER SCIENCE SYSTEMS ANALYSIS ▸ A computer system consists of ▸ the hardware ▸ the software ▸ the data ▸ the people ▸ …and the ways they interact
3. COMPUTER SCIENCE SYSTEMS ANALYSIS When a company needs a computerised solution to a problem, they call on a systems analyst to oversee the creation, development, testing and implementation of a new computer system and possible further improvements. 
 Systems analysis involves a detailed study of an existing system and specifications of a new system Systems design involves the design of the new system (hardware, software, data and people)
 

4. COMPUTER SCIENCE SYSTEMS ANALYSIS One of the jobs of the systems analyst is to make sure the new system is: ‣ Cost-effective - the new system should generate more money than is spent on installing and running the new system! ‣ Completed on time ‣ Completed within a budget agreed with the management of the company.
5. COMPUTER SCIENCE THE SYSTEM LIFE CYCLE This system above is sometimes referred to as the cascade or waterfall model of systems analysis. The stages of creating a new computer system is called a system life cycle.
6. COMPUTER SCIENCE 1. DEFINITION OF A PROBLEM Without a detailed definition of the problem we are trying to solve, people are often unsure of what it is they are trying to achieve. 
 -aims and objectives of new system must be stated
 e.g. cost reductions, better service to customers; greater volume of business transactions etc. The final results will be measured against these to decide the effectiveness of the solution.
7. COMPUTER SCIENCE 2. FEASIBILITY STUDY A preliminary investigation is essential to determine whether a project is technically and economically feasible. Some projects may not be. Technological Feasibility – Do the technologies exist? Is it practical? Economic Feasibility – Is the approach cost effective? Legal Feasibility – Is there any legal constraints with the new proposed system? Operational Feasibility – Are the current work practices and procedures are adequate to support the new system? Schedule Feasibility – How long will it take to create the new computerised system. Can it be done within a desired time frame?
8. COMPUTER SCIENCE 3. INVESTIGATION AND ANALYSIS The systems analyst will need to study the present system in detail: ‣ What data is needed and how is it collected and stored? ‣ What hardware is used? ‣ What software is used? ‣ Who does what? ‣ What are the problems? It would be difficult to design an effective new system without knowing in detail how a business works and what problems it is encountering.
9. COMPUTER SCIENCE 3. INVESTIGATION AND ANALYSIS Methods of investigation may include: ‣ Questionnaires to staff and management Fast method of getting information as many questionnaires can be handed out at the same time. Questions have to be simple ‣ Interviewing of staff and management; More detailed questions can be asked. Questions can be asked based on responses to previous question ‣ Observation of procedures (invoicing, accounting etc) Watching people at their workplace can provide a lot of useful information about how a system works and what the problems are. ‣ Studying of documents; Documents may include user manuals/guidelines, Codes of Conduct, paper files, invoices and receipts - even notices on the wall
10. COMPUTER SCIENCE 4. DESIGN The systems analyst will need to create a detailed design for the new system. Design elements that will need to be considered are: ‣ Data ‣ Input ‣ Processing ‣ Output
11. COMPUTER SCIENCE 4. DESIGN The systems analyst will need to create a detailed design for the new system. Design elements that will need to be considered are: ‣ Data ‣ Input ‣ Processing ‣ Output
12. COMPUTER SCIENCE 4. DESIGN Data ‣ What data needs to be stored? ‣ How is the data collected? Automatic? e.g. barcodes, OMR etc Design of new data capture forms ‣ Design of the new database
13. COMPUTER SCIENCE 4. DESIGN Input ‣ How is the data input? Keyed in? Automatic methods? ‣ Design of data validation methods Processing ‣ What processing needs to be performed on the data ‣ New programs will need to be designed ‣ What type of system? - batch, real-time
14. COMPUTER SCIENCE 4. DESIGN Output ‣ Screen designs for displaying output ‣ Design of printed reports Hardware ‣ Design of appropriate hardware ‣ Positioning of hardware ‣ Network configurations
15. COMPUTER SCIENCE 4. DESIGN Software ‣ Which software will be installed? ‣ What HCI (Human computer Interface?) ‣ GUI, Menu, Command Line, Speech? Security ‣ How will the system be kept secure?
16. COMPUTER SCIENCE 4. DESIGN Forms for input should be: ‣ Be clear and uncluttered - careful use of space needed. ‣ Be easy to understand - no ambiguous questions ‣ Give clear instructions - Eg the format of data should be clearly indicated. ‣ Use language appropriate to the user - e.g. Don't use difficult language for school pupils. ‣ Not be too big - or people will not use them ‣ Have help facilities - either printed or online. ‣ Look attractive - careful use of colour and graphics.
17. COMPUTER SCIENCE 4. DESIGN Reports for output should be: ‣ Be concise - don't provide useless information. Relevant information should be easy to find. 
 ‣ Have a title - so that it is easy to see what information the report is giving. 
 ‣ Have a clear purpose - masses of data can be meaningless. 
 ‣ Be organised - so it is easy to understand 

18. COMPUTER SCIENCE 5. DEVELOPMENT / CODING / TESTING Program specifications are given to programmers who code the programs, test and debug them. There are 3 main types of testing... alpha, beta, acceptance testing. Alpha testing is where the final program is tested by the company by people who have not worked on the project.
 Beta testing is where a small group of users outside the company use the software / program to see if they encounter any bugs or usability problems not picked up during the alpha testing. Acceptance testing is when the user tests the final program against every requirement in the requirements specification.
19. COMPUTER SCIENCE 6. IMPLEMENTATION ‣ Installing and testing the overall system. ‣ Staff training ‣ Changing over to the new system is often done by parallel- running the new system with the old one until fully operational. ‣ Direct changeover The old system is stopped and the following day the new system is used. This could be disastrous if there are errors in the new system!
20. COMPUTER SCIENCE 7. MAINTENANCE All systems need to be maintained - making sure the system continues to function correctly, modifications made, errors corrected, documentation kept up-to-date. Perfective All programs can be improved. Programs may be improved to run faster, give better response time to customers etc.
 Adaptive There may be changes in the company. All businesses expand or contract, number of customers may increase, number of product sold may increase, new branches open etc Corrective Problems may arise which have been hidden for a while and then suddenly arise. They would need correcting.