Data, information, passive and interactive systems
Data verses information
Data comprises of a set of codes that have a structure. For example, you might have a set of integers (whole numbers) or a set of real numbers (numbers with a fractional part) or a set of strings (each string is made up of an ASCII character) and so on.
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- Here is an example of some data: 12, 45, 34, 23, 44, 91, 5
- Here is another example of data: 12.66, 14.89, 3.65, 611.00, 723.04, 76.01
- Here is yet another set of data: Fish, Chips, Sausages, Beans, Peas
Each set of data has a structure. What the data lacks, however, is an interpretation. What does the data mean? It is not until you are told that the first set of numbers refers to the number of cars sold by Cooper's Garage in each of the last seven months that you have information. It is not until you are told that the second set of numbers refers to a bank customer's balance over the last six weeks that you have information. It is not until you are told that the third items in the list are the most popular sellers in the local chip shop that you have information.
Data is a set of coded, structured symbols. Information is when data is given a context.
Passive and interactive information systems
In the context of computing, an 'information system' is any computer system that has data in it that can be rearranged and accessed by users in the form of information. Information systems hold data on secondary storage devices, for example, on a CD or a hard disk. Sometimes, the data held on storage devices can be changed by users. Sometimes it cannot be.
If the information held in storage can be accessed but not changed, it is known as a 'passive information system'. An example of this kind of storage system would include an encyclopedia held on a CD. You can access the information on the CD. You can even search through it. But you can't actually change the information on it.
Some information systems are known as 'interactive information systems'. This is because you cannot only access the information, you can change it, too. An example of this is a school's database of pupils used by the secretary. The secretary can access any pupil's details. They can even search through all of the pupils' records to find ones that match some particular criteria and they can change the details held on the database, for example, when a pupil moves house. Another example might be a shop's database of products. It can be searched to see what products are available and it can be changed, perhaps as part of a stock control system. Each time an item is scanned at the checkout the number of items available is reduced by one. New products can also be added to the database and ones that are no longer sold removed.