Topic 1- Data and Quality of Data

Topic 1- Data and Quality of Data

Topic 1- Data and Quality of Data

Data can be:

  • Numbers
  • Words
  • Images
  • Sound
  • Videos

Definition of Data

  • Data consists of raw facts and figures
  • These raw facts and figures are meaningless because they lack relavance
  • If you look at data, it is either no use to you or not in a form that you can use


Data processed by the computer

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Topic 1- Data and Quality of Data

Processed can mean:

  • Having calculations perfromed on it
  • Converted to give it meaning
  • Organized in some way

Information is data that has been processed in some way to give it meaning and context, for example, sorting a list of names into alphbetical order


Obtained from information by appying rules to it

Example: Here is a number: 39, This is data because there is no meaning. If this is a child's temperature in Celsius, this is information. If we apply the knowledge that normal temperature is 37 we now know that the child should see a doctor

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Topic 1- Data and Quality of Data

GIGO (garbage in garbage out)

Means if you enter incorrect data into the computer then the output from the computer will also be incorrect

Ways data can arise:

  • From the results of an experiment
  • From automatic measurements using sensors
  • From a transaction
  • From a survey

Encoding and the Storing of Data

  • Encoding of data
  • Data is often coded when it is collected on input into an ICT system
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Topic 1- Data and Quality of Data

The reasons for this are:

  • Coded data is quicker to type in
  • It takes up less stroage space on a disk
  • It is easier to do a validation check
  • Faster to access data that is coded
  • It is quicker to send data over a network

Examples of encoding:

M and F- Male and Female

GB, D, IR- Great Britian, Denmark, Ireland

Storing Data

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Topic 1- Data and Quality of Data

Advantages of using ICT for storing data:

  • Less storage space is needed
  • Data is easily copied
  • Easier to backuo
  • Easily transferred on networks
  • Fast access to stored data
  • Data can be put into a secret code when stroed (encrypted)

Disadvantages of using ICT for storing data:

  • Copying data means copyright holders lose out on money when music, games and videos are copied
  • Data can be copied quickly, means personal data can be stolen
  • Rekuabce on networks
  • Training needed
  • Security problems
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Topic 1- Data and Quality of Data

Data Validation

  • It is necessary to take as many precautions as possible to make sure that is it accurate. In this section we will look at techniques used to reduce the errors in data

How eeros can occur:

Errors in data can occur during:

  • Transcription i.e. mishearing words
  • Input i.e. mistyping words
  • Processing i.e. mistakes in formulas
  • Transmission i.e. data fetting corrupted as it travels through wires

Definition of Data Validation

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Topic 1- Data and Quality of Data

  • Validation is a check performed by a computer program during data entry. It ensures the data is sensible and reasonable. Validation is performed by the computer programme being used and consists of a series of checks called validation check

Types of Validation checks:

  • Validation checks are used to restrict the user as to the data they can enter. There are many different validation checks each with their own special use
  • Data type checks- check that the data type being entered is the same data type as that entered for that fiels
  • Presences checks- to check that a field had been entered
  • Range checks- are performed on numbers to check that a number being entered is with a certain range
  • Format checks- to make sure they mmet set criteria

Data Verification

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Topic 1- Data and Quality of Data

  • Verification means checking that the data being entered into the ICT system perfectly matches the source of the data

Methods of Verification

  • Visual check/ Proof reading- this involves one user carefully reading that they have typed in and comparing it with what is on the data source for any errors which requite correcting
  • Double entry of data- using the same data source to enter the details into the ICT system twice and only when the two sets of data are identical will they be accepted for processing
  • Parity Checking- involves checking data after it has been sent through a wire or wirelessly. These check that the data has not corrupted in any way
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