OCR AS ICT Unit 1 Chapter 1

This is all the information you need to know for chapter 1 of the OCR Unit 1 ICT Exam (G061).

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  • Created by: Sqd3
  • Created on: 16-04-14 12:26

Chapter 1 - Data, Information & Knowledge

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.

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Chapter 1 - Representation Methods

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.
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Chapter 1 - Representation Methods (Continued)

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 
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Chapter 1 - Representation Methods (Continued)

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.
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Chapter 1 - Data Types & Sources of Data

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.


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Chapter 1 - Sources of Data (Continued)

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.
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Chapter 1 - Static and Dynamic Data

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.
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Chapter 1 - Quality of Information

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.

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Chapter 1 - Encoding Data

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. 
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Chapter 1 - Encoding Data (Continued)

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. 
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Chapter 1 - Validation

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
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Chapter 1 - Validation (Continued)

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 CheckEnsures that data has been entered into a field.
  • Lookup CheckLooks 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.
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Chapter 1 - Verification

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
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Chapter 1 - Archiving & Backing Up

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.
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Chapter 1 - Costs of Producing Information

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.

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Chapter 1 - Input, Processing and Output

(http://technologytheorieswiki.wikispaces.com/file/view/inputoutput.jpg/319552666/inputoutput.jpg)

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Chapter 1 - Input, Processing and Output

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).
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Chapter 1 - Input, Processing and Output

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. 

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Comments

samia

best resource so far

samia

best resource so far

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