Chapter 1.11 Characteristics of Information Systems
1.11 (a) Passive and Interactive Information Systems
An information system is a system that provides information according to a user’s requests.
Passive information systems.
Passive information systems are systems that will answer queries based on the data that is held within them, but the data is not altered. A simple example would be an electronic encyclopaedia where queries can be used to search for data and much valuable information can be learned, but the user is not allowed to alter the data. Another example would be the student file in a school that can be accessed by members of the teaching staff to find out where a student is at a particular time of day, or to look up their telephone number in order to contact the parents. The database of information is a valuable resource but it is not possible for an ordinary teacher to alter it.
Interactive information systems.
An interactive system is one in which data can be entered for processing, which may alter the contents of the database. An example would be the school secretary updating the attendance record of a pupil in the pupil file. In commerce, a stock control system in a supermarket is an interactive information system because it not only gives information like the price and the description of the goods for the till receipt (passive), but also updates the number in stock immediately (interactive) so that when the next item is sold the number in stock has already been altered.
1.11 (b) Management Information Systems
A management information system is software that allows the managers within a company to access and analyse data.
The management within a company, or any other organisation, is usually working on two levels. These levels may be different levels of management or may be the same people but with two different tasks. One is the day to day management of the organisation, keeping track of invoices, ensuring that the business has enough stock, arranging for the workers to be paid… The other is the strategic management, making decisions about what items of stock to keep, what new items to stock, what to discontinue…
The first of these management tasks is condition driven. The information system can be used to trigger decisions that have to be made. A certain item is reported to be low in stock by the system, requiring a decision to be made as to whether to reorder and how many to reorder.
The second of these management tasks is to look at the wider picture. To extract information from the system which can inform wider decisions like should an item be stocked, which areas of the business are doing well and which are not, which workers are having to do a lot of overtime which may point to the need to increase staff in that sector.
Such reports are termed Strategic level reports because they inform the executives who need to decide the strategy that the company is to follow.
1.11 (c) Applications requiring Batch Processing/Rapid Response
Batch processing.
A batch processing system is used when the output does not have to be produced immediately. Other factors are that the application will tend to use a large amount of data, that processing will tend to be of the same type for each set of data and that human intervention is not necessary. In section 2 we saw that the perfect example of batch processing is the payroll system, and nothing has changed because we are in a different section.
Rapid response processing.
Real time processing can be thought of as being used in process control where the results of the process are used to inform the next input. A good example would be the control of a robotic machine on the production line. The other example is in information systems where it becomes necessary to update the file of information before the next enquiry is dealt with. The classic example is the airline (or theatre) booking system. If a customer enquires whether there is a seat available on the flight, and in response to a positive reply decides to buy the ticket, then the number of tickets now available must be updated before the next person makes an enquiry, otherwise the second person may be sold the same seat. Similarly, the mail order company will need to change the number of items in stock before the next query arrives.
1.11 (d) Expert Systems
An expert system is one which contains as much data as possible about a restricted knowledge area. The data is collected from as many expert sources as possible and stored in the system, in this way it is hoped that the system contains all the knowledge about that topic that there is.
For this reason, these systems are sometimes called knowledge systems. The use of expert systems relies on the belief that for any given area of knowledge there are rules that always apply to that knowledge and that they can be applied according to a logical ordering. This can apply to scientific principles well, for example if there is a rule that oil is always found between two particular types of rock strata, then if the system identifies the strata it can determine, according to the rules, where to drill for oil. Because it follows scientific principles, oil exploration is a good example of the use of expert systems. It is particularly useful because the data that is collected is logged on computer systems when it is collected so it seems sensible to use this information as input to the expert system because it is already in computer readable form.
Expert systems need four parts in order to produce sensible results:
· A lot of data. This is all the data that the system has been told about the application area. It is called the knowledge base. Imagine a medical expert system. The knowledge base would be created by collecting all the knowledge about diseases from all the best doctors in their fields.
· A set of rules that apply to the situation. “If the patient has a headache then they should take two aspirin”. This is called the rule base.
· It is no good having a set of rules and a big collection of knowledge if there is nothing that can apply the rules to the knowledge to come up with sensible solutions. The thing that does this called the inference engine. This is what decides whether the patient should be given aspirin. Some people are not allowed aspirin, certainly not if the patient has an ulcer or…, it is the inference engine that checks through everything to find out what will fit all the rules.
· After a decision has been made, the system must be able to tell the person what the result is. The fourth part of the system, therefore, has to be an HCI.
Example Questions
1. Explain the difference between a passive information system and an interactive information system, giving an example of each. (4)
2. A company payroll system uses a personnel file among others.
a) Explain the difference between batch processing and rapid response processing. (2)
b) Explain how batch processing and rapid response processing can both be sensibly used in the context of the personnel file being used to calculate the payroll. (4)
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