ICT (Information, Systems and Applications) Chapter 1 Definitions

Data is raw facts and figures before they have been processed. This means the raw facts and figures have no meaning.

Example: BAT56& OR 6783847BB

• Data can be alphanumeric characters, sound or graphics
• Data is raw facts and figures
• data has no meaning

=Information is made by taking the data and processing it. 

There is a formula for information:

Information = Data + Structure + Context + Meaning

• Data - the raw facts and figures
• Structure - how the data is presented
• Context - an environment where our prior knowledge and understanding can make sense of the data
• Meaning - data in the correct structure and placed in the right context
• Knowledge - the application of information to a situation.

Advantages:

• Clear to understand
• Lots of detail

Disadvantages: 

• Need to be able to read
• Need to understand the language
• Can be confusing - level of language
• Lots of text cannot be read quickly

Advantages:

• Multilingual - do not need language to understand an image
• can match what you see - physical shapes

Disadvantages:

• Can be confusing if you don't know the symbols
• some symbols dont mean the same thing in different countries

Advantages:

• No fixed position
• No line of sight required
• Good for visually impaired people

Disadvantages:

• No good in large ares - distortion of sound
• Usually language based
• May not know the sound - different alarms
• Need to be able to hear

Advantages:

• Lots of information conveyed
• Not language dependant
• Can exemplify text

Disadvantages:

• Linear
• Problems if sound

Advantages:

• Can allow data to be kept secure
• Can be used in noisy places
• Similar to graphics

Disadvantages:

• Need to be able to see the lights
• Combinations of lights may need to be known to be understood

The boolean data type can only hold one of two values - True and false.

This data type contains numbers which will have decimal places. It is used to hold numbers where precision is important.

This data type contains whole numbers with NO decimal places. It is used where accuracy may not be of vital importance or the value allocated is specifically a whole number.

This is any alphanumeric character. This includes numbers, text and symbols. Text is used to convey basic information. Most importantly if you store anything as a string, no mathematical calculations are performed on it, i.e. Telephone Number

This contains numbers and letters, which, depending on the format used, displays the date or time to different degrees of accuracy.

Direct (Primary) data is collected from an original source. It is often physically collected by yourself.

Advantages:

• The source and collection methos is known and verified
• The exact data required can be collected
• Can change the data being collected in response to answers

Disadvantages:

• May not get a large range of data
• Data may not be available - Location/Time

Data that has been used for a purpose that is different to that for which it was originally collected. Or the people or companies involved in collecting the data are different to those who use it.

Advantages:

• Large range of data available that could not have been collected directly
• Data available from different locations and time periods
• Analysis might already have been completed on some of the data.

Disadvantages:

• Do not know is any bias was placed on the collection
• Cannot be certain of accuracy of the recording of data
• May not have all the information on how, when and where it was collected to make a valued opinion on its usefulness
• If the information was not originally collected, may not be able to get hold of it

The data needs to be accurate. If it is not accurate you can not rely on the information  it provides.

The information must be relevant, if you have some information but it doesn't relate to the topic it is worthless. Having information that is not relevant can be a disadvantage, it increases the volume of data, which means longer is needed to look at it all.

The information may be too old, information can change over time. If you know the information is from the past it may not be relevant now. 

If you only have part of the information then it is worthless. Data requires a context, structure and meaning for it to have value and to be useful.

If information is presentated in a way that you can't understand or you can't find what you are looking for, it loses value. The presentation might be improved by sorting the data, or using a different method of representation.

You can be given too much data, or too little. The volume of data determines whether you have enough to make a decision or too much. If you have too much it can be difficult to find what you require.

Encoding data is taking the original data and storing it in a different representation. What it stored is not the actual data but a representation of it. 

.i.e. Blue Jeans Size 8 ---> BJ8

Monday - Mon

DIsadvantages:

• The precision of the data entered is coarsened - it makes the data less accurate.
• Limits 'choice' for example hair colour - Blonde .vs. Strawberry blonde
• It is impossible to set up a database to analyse every possible answer
• Need to know codes
• Encoding Judgements - everyone different
• Limit to number of codes
• Difficult to track errors

Advantages:

• Memory requirements are far less
• It's quicker to enter a code
• Codes can easily be tagged, so can be found in a database
• They have a precise structure
• is more secure
• Data can be validated
• Organises the data as it has a standard format

• Range Check - sets an upper and lower boundry for the data. The data entered must lie between these two values
• Type Check - this makes sure the data is the right type; integer, boolean, real, string, date...
• Presence Check - these make sure check that there is something entered (if needed) and will insist a value is inserted
• Length Check - ensures that the data cannot be more than the set number of characters
• Look Up Checks - it takes the value entered and compares it against a list of values in a seperate table, it can return a confirmation. 
• Picture Checks - This is also known as a format check, it makes sure the combination of numbers and letters are in the right order. Because the mix of numbers and letters means that a type check cannot be applied.
• Check Digit - a check digit is calculated using a set of numbers and then aded to the end of them. If the check value is the same it will continue processing, if not a value needs to be re-entered.

• Double Entry - this means that the information is entered twice, and if the second piece doesnt match the first the computer will ask for it again twice. But this is not always good, as the person could enter the same, wrong piece of data.
• Manual Verification - is proof reading the data. It means visually comparing the source data and the typed data to spot any differences. 

Backing up is making a copy of the original data incase of the original becoming corrupted by viruses or the files being deleted.

The back up is often kept else where, large companies often have large warehouses full of servers.

Back Up devices:

• Magnetic Tape
• RAID
• Floppy Disk, Memory Card
• CD - RW

Archiving is for long term storage of data that is not required immediately. It is stored for future reference.

Hardware 

• initial costs
• Maintenance
• Upgrade and Repair

Software

• Purchasing Licences - for desktop publishing, graphics software...
• Technical Support
• Training costs, so staff know how to use the software features
• Upgrades

Consumerables

• Ink and Paper

Personnel

• People working for the organisation
• The people needed to collect, collate, enter, process and output the data and information
• Software training costs
• Staff covering costs
• Expensive costs

Input - this is taking information that is external to the system and entering it into the system. This may be manual input (keyboard) or automated input (OMR). Though it may also be input by electronic means (CD/Disk)

Processing - this is an action performed on the data. This includes sorting, searching and calculations on the data.

Storage - This is where the data is held. This may be the input data, or data held on the system that is required for processing.

Output - This is taking the information from the system and outputting it. The method may result in a printed output, output on screen or and electronic output.

Feedback - This is where the output from the system forms part of the input to the system, Feedback is usually applied to real-time situations.