OCR AS ICT Unit 1 Chapter 1

Data: The raw facts and figures without meaning.

• Example: 093234 RDJKAE912

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Information: Processed data + [Context] + [Structure] + Meaning.

• Context: Environment in which the data makes sense.
• Structure: The presentation of data, including any formatting.
• Meaning: The understanding of what the data relates to.

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Knowledge: The application of information to a situation.

Text:

• Clear to understand.
• Lots of detail.
• You have to be able to read to understand it.
• You need to understand the language.
• Lots of text can't be read quickly.

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Graphics:

• Don't need language to understand an image.
• Can match to what you see.
• Confusing if you don't know the symbols used.
• Some graphics can have different meanings > Misunderstanding the true representation.

Sound:

• No fixed position.
• No line of sight required.
• Good for visually impared people.
• Not good in large areas - distortion of sound.
• Usually language based
• May not know the sound - e.g. different alarms have different sounds
• Need to be able to hear - wouldn't be suitable for those who are audio impaired.

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Moving Pictures:

• Lots of information conveyed
• Not language dependent
• Can exemplify (illustrate) texts 
• Linear - if you do not see the beginning you may not understand
• Problems if there is sound 

LED:

• Can allow data to be kept secure
• Can be used in noisy places
• Similar to graphics
• Directional (need to be able to see the lights)
• Combinations of light may need to be known to be understood.

There are 5 data types:

• Boolean: One of only two values (e.g. true/false).
• Real: Numbers with decimals. (e.g. 87.09)
• Integer: Numbers with no decimals. (e.g. 43)
• Text/String: Alphanumeric characters inc. numbers/text & symbols. (e.g. Good Luck)
• Date/Time: Numbers and letters. (e.g. 08/11/13)

There are 2 sources of data:

• Direct (primary): 
  • Collected from an original source - data is physically collected by you.
• Indirect (secondary): 
  • Data that has been used for a purpose different to what it was originally collected.
  • The people/firms involved in collecting the data are different to those using the data.

Direct (primary) Source:

• Source and collection is known and verified.
• Exact data required can be collected.
• Data being collected can change in response to answers.
• May not get a large range of data.
• Data may not be available - location/time.

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Indirect (secondary) Source:

• Large range of data is available.
• Data can be available from different locations and time periods.
• Analysis might have been completed on some of the data.
• Don't know if any bias was placed on the collection.
• Can't be certain of accuracy of recording of data.
• May not have all information about how,when and where it was collected.
• If information was not originally collected > may not be able to get hold of it.

Static Data: Data that doesn't change, once created. (e.g. CD)

• Does not require internet access
• More reliable information source
• Data can't be updated very quickly.
• Suitable computer may be needed.
• Need to buy the CD/magazine

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Dynamic Data: Data that can be changed and updated, once created. (e.g. Website)

• Large volume of information
• Available at any time from any location
• Data can be updated very quickly.
• Need internet access
• Not always reliable
• Internet may not be working > difficulty in accessing pages.

Six Factors to determine the quality of information:

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• Completeness: Information must be in whole order to understand.
• Accuracy: Information needs to be correct. If it is not accurate you cannot rely on it.
• Relevance: Information must relate to the topic or it can increase the volume of data and time to look at.
• Presentation: Information must be presented so that we can understand.
• Age: Information from the past may not be relevant today. Age can affect the accuracy of information.
• Level of Detail: Enough information must be given.

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 - Remember them as C.A.R.P.A.L.

Encoding: Taking the original data and storing it in a different representation.

• Methods can involve shortening, symbol replacement or abbreviations.

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Advantages:

• Less memory requirement: storing less information, therefore less memory is required.
• Security: If the codes are not apparent then it is difficult to know and understand the      meaning of the codes. 
• Speed of input: the codes take less time to enter, therefore it is quicker to input a large volume of data. 
• Data Validation: since the codes follow a strict set of numbers and letters they are easy to validate. 
• Organisation of data: If the data is standardised format then it can be compared and organised. 

Disadvantages:

• Precision of data coarsened: An example being, Light Blue encoded as Blue.
  
• Encoding of value judgements: An example being, 'Was the film good?' to be encoded as a judgement of 1-4. This will be encoded differently by different people and makes comparisons difficult. 
  
• The user needs to know the codes used: If the user does not know the codes they  cannot  use them. 
  
• Limited number of codes: If codes are made up of a range of letters and numbers the  options will be limited. 
  
• Difficult to track errors: Validation will ensure the code is entered correctly but the nature  of the code will make it difficult to see if the code is actually correct. 

Validation: A check that is performed as the data is being entered. It tries to prevent entry of any data that does not conform to pre-set rules.

It ensures that the data that is entered is:

• Sensible
• Reasonable
• Within acceptable boundaries
• Complete

7 Types of Validation Methods:

• Range Check: Checks that data entered in within a pre-determined range.
• Type Check: Checks that data is of the correct type.
• Length Check: Checks the number of characters entered to ensure that the max. and min. length is achieved.
• Presence Check: Ensures that data has been entered into a field.
• Lookup Check: Looks up the data in another table to ensure it's valid.
• Picture Check: Ensures the location of the characters is the same every time.
• Check Digit: Mathematically calculated using sets of numbers & then added to the end.

Verfication: Ensuring that the information on the original source is the same as the object document.

• It CANNOT ensure the accuracy of data entered.
• It CAN ensure that data is entered correctly, not that it is correct.

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2 Main methods of Verification:

• Computer Verification (Double Entry): Data is inputted twice and the computer matches the two sets of data looking for mistakes.
• Manual Verification (Proof Reading): Data is manually compared against the source.

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2 Main errors of Verification:

• Transcription Error: mistakes when copying
• Transposition Error: two characters typed in the wrong order

Back-up: Keeping a copy of the current data

• Used to restore current data if there is a system failure.
• Done on a regular basis.

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Archiving: Storing data for long-term storage that isn't required immediately.

• Original is deleted once archived, to free up hard drive space and improve the performance of the system.
• Done less than backups.

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Process of Archiving Files:

• 1) Copy the file onto the archival media.
• 2) Verify the copied files.
• 3) Delete the original files.

Hardware: Can be used to collect the information, process it and output it.

• Initial costs and ongoing costs for maintenance and repair.

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Software: Software licences need to be purchased.

• Training costs - to train users how to use the software.

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Personnel: Costs related to people working in the business.

• Training Costs, Hiring Costs and Time.

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Consumables: Items that get used - paper, printer ink and electricity.

Input: Taking external information into the system.

• This may be manual input or automated input (e.g. OMR). It may also be input by electronic means - via a network or CD/disk.

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Processing: This is an action performed on the data.

• Processing can include sorting, searching or performing calculations on the data.

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Output: This is taking information that was in the system and outputting it.

• The method used may result in printed output, screen output or electronic output (e.g. disk/CD).

Storage: This is where data is held.

• It may be the data that has been input, data required during processing or the results of processing. This is data that is still within the system.

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Feedback: This is where the output from the system forms part of the input to the system.